My 5e D&D party is on an extended set of encounters in which we won't be in civilization for a while, and my DM and I have gone back and forth about the new spells my Wizard gains after leveling up. I've looked at this post and this one but they aren't exactly what I'm looking for.
In the PHB, a wizard gets two additional spells in his or her spellbook when leveling up. My DM argued they wouldn't just appear, and should involve some time, at least a long rest so I can write down what I'd been pondering as I adventured. I think that makes sense in terms of gameplay, but then kind of feels like wizards would get a disadvantage if other classes don't have to use a long rest to gain the benefits of leveling up. That being said, maybe that's part of the point, to balance wizard's ability to access huge amounts of spells.
Another member of the party pointed out it doesn't really matter, since I'd need a long rest to prepare the new spells anyways. But I'm still interested in anyone's thoughts. Partially for angels-dancing-on-the-head-of-a-pin reasons (which I think are appropriate for a wizard). But also because I was wondering if I'd have immediate access to any rituals I add.
Best Answer
The way I've always thought of levelling up is this: It's an an abstraction of what would really be an ongoing process. A character doesn't instantly get better at a bunch of things once they've killed that 37th orc, they've actually been improving continuously the whole time, so leveling up us really just a 'tipping point' where the increase in skill becomes consistently effective.
In the case of a fighter, it would be them properly internalizing in muscle memory a technique they've noticed makes it a little easier to score a hit in some situations. They've known about it for awhile, but they don't always pull it off right (represented by random dice rolls). When they level up and get that extra BAB, they've got it down, and can do it every time.
For a wizard's spells, I imagine a wizard is constantly experimenting and doing research 'in the background'. When they level up, and get a new spell they've actually been working on that spell for a long time. They've only just has that final 'ah-ha!' moment to make the spell effective and reliable - good enough to use consistently. They still can't use it right away, because they need to finalize their notes and prepare it.
I also figure that levelling up doesn't neccessarily mean they can do the new thing 100% perfectly. +1 BAB (usually) doesn't mean you hit some enemies 100% of the time, so dice rolls still represent trying a new thing and failing. Things like feats and class features fit into this less well, but I like to think this explains things well.