Resource management is a very minor thing in a sense because it makes an assumption that you have X available against Y encounters per Z. Though when it comes down to a more micro level such as within that day then resource management becomes important.
And then you can browse through any thread talking about resource management and you'll find players and DMs divided on that issue.
Then there's this giant nugget.
Quote
Jeremy Crawford: Changing a skill and changing your subclass are great examples of the fun nuggets we like to include in a book like this that weren't necessarily in Unearthed Arcana, because we always like there to be a few surprises. People saw a version changing skills back in Unearthed Arcana in our Class Feature Variant article where we explored this as an option, customized for each class, but we decided when finishing the book, it was better to just provide a general rule for everybody. Changing your subclass, though, is truly something people haven't seen. We give you concrete guidance on when is a good time to change your subclass, how you might go about it, some comments for the DM on whether some in-world training should be involved in this transformation of your character. This is the kind of thing many DMs let their players already do with their characters, but what we often find is that some DMs are hesitant to allow this sort of liberty unless we, basically, give "official permission" to do it.
So this is really us telling DMs, "It's okay to let people do this." You know? If they find their subclass just isn't playing the way they'd hoped, or if there's been a major story transformation for their character, changing your subclass is a great way to address those different things... These all go under what I often refer to as the "follow your bliss" umbrella of giving people the permission – and the encouragement – to make tweaks that will enhance their enjoyment of their character and of D&D more broadly.
