How to permanently set refresh interval for top command?

Personal configurations such as this may be saved to your ~/.toprc file by hitting SHIFT+W in the interactive top session.

From man top (or online):

 6b. PERSONAL Configuration File
   This  file is written as `$HOME/.your-name-4-top' + `rc'.  Use the
   `W' interactive command to create it or update it.

Why not just launch top with a preset interval like this top -d 5. Which will make top start preconfigured to update every 5 seconds.