How much does time matter in Might and Magic VII?

I can tell that time matters in some cases, though not sure if I know all about it.

There are time-limited quests, like the ones present after the war starts and you need to take side. But the limits aren't too pressing.

But if you'll be going too fast, then I think you could run out of experience: no strength to go to more advanced places, while mobs in the already visited ones will respawn only after some period of time. But I am saying this from MM6 experience, maybe (and most likely) MM7 is simply easier so this doesn't matter.

Also, there's age value, but I don't remember what it affects and if.

Regarding spending potions, strictly speaking, this isn't wise since you spend larger monetary value (potions are probably more expensive than food), unless you take time into account and play like you need to finish it faster in universe time.

Source: http://m.gamefaqs.com/pc/143119-might-and-magic-vii-for-blood-and-honor/faqs/27528

Time is yet another concept in Might & Magic VII that must be addressed. As you might have noticed, time passes in this game. And there's really nothing you can do about it. The game starts on January 01, 1168. There are twelve months, each having 28 days. Time passes at the rate of approximately one game minute for every two real-life seconds. Of course, time also passes quite rapidly when you rest, travel from region to region, or just simply by waiting. You can advance the speed of time by pressing the R key (default) and clicking on a denomination of time in which your characters are instructed to hang around where they are and wait (5 minutes, an hour, or until the next 5:00 AM). Note that unlike camping, your characters can wait without fear of being ambushed by enemies, although you still cannot choose to have them wait while enemies are near.

Anyways, as time progresses, you are inevitably going to start noticing some changes, which aren't necessarily bad, but you'll still want to be prepared for them. First off, the most noticeable effect time has on your travels concerns shopping. Whether shops need it or not, they will restock their wares once every two weeks. However, for the two-week clock to begin, you must enter that shop. After the shop restocks, you must enter it yet again to start the clock again, and so on. This phenomenon, otherwise known as "respawning", can also be applied on a much larger scale. Whenever you enter a certain region, it starts a clock on that region. When that clock this two years, the region respawns. Enemies and treasures will both repopulate the map at this point, meaning you can go back for more experience and gold if so desired. Also note that the one area that will never respawn is inside Castle Harmondale. This is very important, as you can use the treasure chests inside the castle to store your excess goods.

By the by, on a somewhat separate note, section III.C. of the FAQ is also strictly timed. It is the only part of your quest with time several time limits working at once, so you are advised to go into that particular area of the walkthrough fully prepared.

Aside from what I've already mentioned the only other real effect time has on you is age. Your characters, believe it or not, will age just as people would in normal life. Your characters age naturally as the years pass by, and certain forces throughout the land also have the capability to magically age your characters. Your actual age and your current (magically-enhanced) age are both statistics kept on a characters stat screen. In the event that your current and actual age are different, your current age will be listed in green. It is possible to reverse unnatural aging with the black potion Rejuvenation. Natural aging cannot be reversed.

And so, inevitably, your characters will age as you play through the game. Not that it will have any cosmetic effects on your characters whatsoever- I've honestly seen characters in their thousands looking as young as they day they were 20, which is at the very least profoundly astonishing. Statistics are another issue, however. They remain fine for most of their life, but after awhile, age will begin to alter their statistics. The chart below details how your stats will alter to various percentages of what they once were after reaching certain age thresholds.

+-----------+-------+------+------+------+------+-------+------+
|    Age    | Might | Int. | Per. | End. | Acc. | Speed | Luck |
+-----------+-------+------+------+------+------+-------+------+
|   0 - 49  |  100  |  100 |  100 |  100 |  100 |  100  |  100 |
|  50 - 99  |  75   |  150 |  150 |  75  |  100 |  100  |  100 |
| 100 - 149 |  40   |  100 |  100 |  40  |  40  |  40   |  100 |
|    150+   |  19   |  10  |  10  |  10  |  10  |  10   |  100 |
+-----------+-------+------+------+------+------+-------+------+

Now, a few things are apparent from this chart. For starters, your characters will be pretty much fine until age 50, and that's when age this them like a ton of bricks. There's a bad over-the-hill joke just waiting to be made here, but I digress. Though the odds are fairly slim that your characters will actually break the 50-year age point, it's actually not such a bad deal for your magically-inclined characters, if you can handle the slight dip in Might and Endurance. From age 100 and on, though, your character just gets progressively worse and degenerates into a crippled mess of althzheimers and Matlock reruns.