So the common consensus seems to be that spell slots and the restrictions that come with them are an in-universe truth that characters are aware of, to varying degrees. But that implies a few strange things about wizards, right?
If I'm an archmage, a high-level evil wizard or something along those lines, there's no way I'd ever use anything beyond cantrips in my day-to-day life, right? If I did, I'd risk getting ambushed while only having access to like half my slots.
So do I ration my spells throughout the day? Seems weird, considering an archmage is supposed to be close to the pinnacle of arcane power and all. And if I do ration my spells, or stick to cantrips, that means there is, for like 90% of the day, very little difference between an in-universe Lvl 3 Wizard and a Lvl 20 Wizard, right?
Obviously I know that this is because the game doesn't simulate actual life with routines and downtimes and all and focuses on a few events per day - but an NPC wizard has a whole day to get through outside of those big events, which are probably really rare besides, and it bothers me and hampers my worldbuilding if I can't get a clear picture of what life is supposed to be like for the people actually living in it.
I don't know if the scope of the question is a bit too vague, but basically what I'm asking is: how does the spell slot restriction affect the daily routine of a wizard in-universe? Do they just use spells when they feel like it and risk getting shanked by a rival who hasn't wasted their spells? Do they ration them out and live on cantrips in the interim? Do they not use them at all in fear of an emergency?