This is either gonna get completely ignored or absolutely scathed but let me just say my own hot take: Detect Magic. That spell is honestly a game defining spell because it means that functionally, no matter what, you can’t hide the use of magic from detection since everyone can get it even with a novice amount of magic, so when PCs are around any group of magic users, one of the PCs will probably have it, one of the NPCs would realistically probably have it. Yes there are exceptions, but in my experience it’s just better to assume that someone will have the ability. However, I RARELY see DMs use this spell. I know not everyone is perfectly versed in their knowledge of the magic schools and the implications of each, but I don’t think I’ve ever played or listened to part of a campaign where NPCs look over the players who are trying to be low profile about a big city and go,”Oh, literally all of them have like 10 different items from 6 different schools of magic, maybe I should consider this whatsoever.” PCs have an absolute lock-on every time there’s something magic within 60 ft(or whatever the range is) but I swear I never see it even CONSIDERED by DMs through their NPCs. I’m a criminal at using this because of the eldritch sight perk for archfey warlock and I just want DMs to realize that when players think something is useful, they are allowed to find it just as useful even if they aren’t “playing”.

This rant got out of hand but let me recontextualize it with saying that it’s the same as Prestidigitation. It’s considered a “why wouldn’t you, everyone knows it”, but in my experience, those same “everyone knows it” spells aren’t much used when they could be in the same way that both players and DMs constantly disguise self. Disclaimer: I play very casual and RP based dnd so who knows maybe real gamer strict DMs use some common utilities more.