Windows 10 slide show shorter than 1 minute
Use the keyboard command Win + R to launch the Run window
Copy & paste this into the Run window:
control /name Microsoft.Personalization /page pageWallpaperand then hit OK. It's a direct route to the old Control Panel setting for slideshow control.You should notice new timing options near the bottom, including 10 and 30-second intervals along with more options for various hours. Just pick the one you want and hit Save changes.
Near the bottom, you should also notice the Shuffle option is now listed here as well. Simply check the box and hit Save changes when finished.
If you want something other than the default options you can follow @Psycogeek's suggestion, you just need to reboot the computer after making the change (I tested his suggestion first and it worked for me).
Since Creators Update that you cannot use the previous command anymore:
control /name Microsoft.Personalization /page pageWallpaper
The alternative is to run:
shell:::{ED834ED6-4B5A-4bfe-8F11-A626DCB6A921} -Microsoft.Personalization\pageWallpaper
...which should be preceeded by explorer.exe if you intend to call it from another process or a shortcut, like so:
explorer.exe shell:::{ED834ED6-4B5A-4bfe-8F11-A626DCB6A921} -Microsoft.Personalization\pageWallpaper
Additionally, in case you are interested, here are a few other potentially useful shell UIDs:
Add Network Location shell:::{D4480A50-BA28-11d1-8E75-00C04FA31A86}
Administrative Tools shell:::{D20EA4E1-3957-11d2-A40B-0C5020524153}
Applications shell:::{4234d49b-0245-4df3-b780-3893943456e1}
AutoPlay shell:::{9C60DE1E-E5FC-40f4-A487-460851A8D915}
BitLocker Drive Encryption shell:::{D9EF8727-CAC2-4e60-809E-86F80A666C91}
Bluetooth Devices shell:::{28803F59-3A75-4058-995F-4EE5503B023C}
Color Management shell:::{B2C761C6-29BC-4f19-9251-E6195265BAF1}
Command Folder shell:::{437ff9c0-a07f-4fa0-af80-84b6c6440a16}
Common Places FS Folder shell:::{d34a6ca6-62c2-4c34-8a7c-14709c1ad938}
Control Panel shell:::{5399E694-6CE5-4D6C-8FCE-1D8870FDCBA0}
Control Panel (All Tasks) shell:::{ED7BA470-8E54-465E-825C-99712043E01C}
Control Panel (always Category view) shell:::{26EE0668-A00A-44D7-9371-BEB064C98683}
Control Panel (always Icons view) shell:::{21EC2020-3AEA-1069-A2DD-08002B30309D}
Credential Manager shell:::{1206F5F1-0569-412C-8FEC-3204630DFB70}
Date and Time shell:::{E2E7934B-DCE5-43C4-9576-7FE4F75E7480}
Default Programs shell:::{17cd9488-1228-4b2f-88ce-4298e93e0966}
delegate folder that appears in Computer shell:::{b155bdf8-02f0-451e-9a26-ae317cfd7779}
Desktop (folder) shell:::{B4BFCC3A-DB2C-424C-B029-7FE99A87C641}
Device Manager shell:::{74246bfc-4c96-11d0-abef-0020af6b0b7a}
Devices and Printers shell:::{A8A91A66-3A7D-4424-8D24-04E180695C7A}
Display shell:::{C555438B-3C23-4769-A71F-B6D3D9B6053A}
Documents (folder) shell:::{A8CDFF1C-4878-43be-B5FD-F8091C1C60D0}
Downloads (folder) shell:::{374DE290-123F-4565-9164-39C4925E467B}
Ease of Access Center shell:::{D555645E-D4F8-4c29-A827-D93C859C4F2A}
E-mail (default e-mail program) shell:::{2559a1f5-21d7-11d4-bdaf-00c04f60b9f0}
Family Safety shell:::{96AE8D84-A250-4520-95A5-A47A7E3C548B}
Favorites shell:::{323CA680-C24D-4099-B94D-446DD2D7249E}
File Explorer Options shell:::{6DFD7C5C-2451-11d3-A299-00C04F8EF6AF}
File History shell:::{F6B6E965-E9B2-444B-9286-10C9152EDBC5}
Font Settings shell:::{93412589-74D4-4E4E-AD0E-E0CB621440FD}
Fonts (folder) shell:::{BD84B380-8CA2-1069-AB1D-08000948F534}
Frequent folders shell:::{3936E9E4-D92C-4EEE-A85A-BC16D5EA0819}
Games Explorer shell:::{ED228FDF-9EA8-4870-83b1-96b02CFE0D52}
Get Programs shell:::{15eae92e-f17a-4431-9f28-805e482dafd4}
Help and Support shell:::{2559a1f1-21d7-11d4-bdaf-00c04f60b9f0}
HomeGroup (settings) shell:::{67CA7650-96E6-4FDD-BB43-A8E774F73A57}
HomeGroup (users) shell:::{B4FB3F98-C1EA-428d-A78A-D1F5659CBA93}
Hyper-V Remote File Browsing shell:::{0907616E-F5E6-48D8-9D61-A91C3D28106D}
Indexing Options shell:::{87D66A43-7B11-4A28-9811-C86EE395ACF7}
Infared (if installed) shell:::{A0275511-0E86-4ECA-97C2-ECD8F1221D08}
Installed Updates shell:::{d450a8a1-9568-45c7-9c0e-b4f9fb4537bd}
Internet Options (Internet Explorer) shell:::{A3DD4F92-658A-410F-84FD-6FBBBEF2FFFE}
Keyboard Properties shell:::{725BE8F7-668E-4C7B-8F90-46BDB0936430}
Language settings shell:::{BF782CC9-5A52-4A17-806C-2A894FFEEAC5}
Libraries shell:::{031E4825-7B94-4dc3-B131-E946B44C8DD5}
Location Information (Phone and Modem) shell:::{40419485-C444-4567-851A-2DD7BFA1684D}
Location Settings shell:::{E9950154-C418-419e-A90A-20C5287AE24B}
Media Servers shell:::{289AF617-1CC3-42A6-926C-E6A863F0E3BA}
Mouse Properties shell:::{6C8EEC18-8D75-41B2-A177-8831D59D2D50}
Music (folder) shell:::{1CF1260C-4DD0-4ebb-811F-33C572699FDE}
My Documents shell:::{450D8FBA-AD25-11D0-98A8-0800361B1103}
Network shell:::{F02C1A0D-BE21-4350-88B0-7367FC96EF3C}
Network and Sharing Center shell:::{8E908FC9-BECC-40f6-915B-F4CA0E70D03D}
Network Connections (in PC settings) shell:::{38A98528-6CBF-4CA9-8DC0-B1E1D10F7B1B}
Network Connections shell:::{7007ACC7-3202-11D1-AAD2-00805FC1270E}
shell:::{992CFFA0-F557-101A-88EC-00DD010CCC48}
Network (WorkGroup) shell:::{208D2C60-3AEA-1069-A2D7-08002B30309D}
Notification Area Icons shell:::{05d7b0f4-2121-4eff-bf6b-ed3f69b894d9}
NVIDIA Control Panel (if installed) shell:::{0bbca823-e77d-419e-9a44-5adec2c8eeb0}
Offline Files Folder shell:::{AFDB1F70-2A4C-11d2-9039-00C04F8EEB3E}
OneDrive shell:::{018D5C66-4533-4307-9B53-224DE2ED1FE6}
Pen and Touch shell:::{F82DF8F7-8B9F-442E-A48C-818EA735FF9B}
Personalization shell:::{ED834ED6-4B5A-4bfe-8F11-A626DCB6A921}
Pictures (folder) shell:::{3ADD1653-EB32-4cb0-BBD7-DFA0ABB5ACCA}
Portable Devices shell:::{35786D3C-B075-49b9-88DD-029876E11C01}
Power Options shell:::{025A5937-A6BE-4686-A844-36FE4BEC8B6D}
Previous Versions Results Folder shell:::{f8c2ab3b-17bc-41da-9758-339d7dbf2d88}
printhood delegate folder shell:::{ed50fc29-b964-48a9-afb3-15ebb9b97f36}
Printers shell:::{2227A280-3AEA-1069-A2DE-08002B30309D}
shell:::{863aa9fd-42df-457b-8e4d-0de1b8015c60}
Programs and Features shell:::{7b81be6a-ce2b-4676-a29e-eb907a5126c5}
Public (folder) shell:::{4336a54d-038b-4685-ab02-99bb52d3fb8b}
Quick access shell:::{679f85cb-0220-4080-b29b-5540cc05aab6}
Recent places shell:::{22877a6d-37a1-461a-91b0-dbda5aaebc99}
Recovery shell:::{9FE63AFD-59CF-4419-9775-ABCC3849F861}
Recycle Bin shell:::{645FF040-5081-101B-9F08-00AA002F954E}
Region and Language shell:::{62D8ED13-C9D0-4CE8-A914-47DD628FB1B0}
RemoteApp and Desktop Connections shell:::{241D7C96-F8BF-4F85-B01F-E2B043341A4B}
Remote Printers shell:::{863aa9fd-42df-457b-8e4d-0de1b8015c60}
Removable Storage Devices shell:::{a6482830-08eb-41e2-84c1-73920c2badb9}
Results Folder shell:::{2965e715-eb66-4719-b53f-1672673bbefa}
Run shell:::{2559a1f3-21d7-11d4-bdaf-00c04f60b9f0}
Search shell:::{9343812e-1c37-4a49-a12e-4b2d810d956b}
Search Everywhere (modern) shell:::{2559a1f8-21d7-11d4-bdaf-00c04f60b9f0}
Search Files (modern) shell:::{2559a1f0-21d7-11d4-bdaf-00c04f60b9f0}
Security and Maintenance shell:::{BB64F8A7-BEE7-4E1A-AB8D-7D8273F7FDB6}
Set Program Access and Computer Defaults shell:::{2559a1f7-21d7-11d4-bdaf-00c04f60b9f0}
Show Desktop shell:::{3080F90D-D7AD-11D9-BD98-0000947B0257}
Sound shell:::{F2DDFC82-8F12-4CDD-B7DC-D4FE1425AA4D}
Speech Recognition shell:::{58E3C745-D971-4081-9034-86E34B30836A}
Storage Spaces shell:::{F942C606-0914-47AB-BE56-1321B8035096}
Sync Center shell:::{9C73F5E5-7AE7-4E32-A8E8-8D23B85255BF}
Sync Setup Folder shell:::{2E9E59C0-B437-4981-A647-9C34B9B90891}
System shell:::{BB06C0E4-D293-4f75-8A90-CB05B6477EEE}
System Icons shell:::{05d7b0f4-2121-4eff-bf6b-ed3f69b894d9}
Tablet PC Settings shell:::{80F3F1D5-FECA-45F3-BC32-752C152E456E}
Taskbar and Navigation properties shell:::{0DF44EAA-FF21-4412-828E-260A8728E7F1}
Text to Speech shell:::{D17D1D6D-CC3F-4815-8FE3-607E7D5D10B3}
This PC shell:::{20D04FE0-3AEA-1069-A2D8-08002B30309D}
Troubleshooting shell:::{C58C4893-3BE0-4B45-ABB5-A63E4B8C8651}
User Accounts shell:::{60632754-c523-4b62-b45c-4172da012619}
User Accounts (netplwiz) shell:::{7A9D77BD-5403-11d2-8785-2E0420524153}
User Pinned shell:::{1f3427c8-5c10-4210-aa03-2ee45287d668}
%UserProfile% shell:::{59031a47-3f72-44a7-89c5-5595fe6b30ee}
Videos (folder) shell:::{A0953C92-50DC-43bf-BE83-3742FED03C9C}
Web browser (default) shell:::{871C5380-42A0-1069-A2EA-08002B30309D}
Windows Defender shell:::{D8559EB9-20C0-410E-BEDA-7ED416AECC2A}
Windows Mobility Center shell:::{5ea4f148-308c-46d7-98a9-49041b1dd468}
Windows Features shell:::{67718415-c450-4f3c-bf8a-b487642dc39b}
Windows Firewall shell:::{4026492F-2F69-46B8-B9BF-5654FC07E423}
Windows To Go shell:::{8E0C279D-0BD1-43C3-9EBD-31C3DC5B8A77}
Windows Update shell:::{36eef7db-88ad-4e81-ad49-0e313f0c35f8}
Work Folders shell:::{ECDB0924-4208-451E-8EE0-373C0956DE16}
For an updated list, look into your OS registry bellow the following key:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\FolderDescriptions
The registry entry at HKEY_CURRENT_USER\Control Panel\Personalization\Desktop Slideshow\Interval does set the interval in milliseconds as suggested by Psycogeek above but to activate you have to go to the setting window (by right clicking the desktop and selecting Personalize) which will appear to show the interval as 10 minutes but it hasn't actually been changed. Just close the setting window and the interval between pictures will change as immediately as specified. Alternatively you have to restart the computer. Change to 10000 decimal for a 10 second interval.