I honestly think that varying chapter lengths are great. I've read several books that throw in super short chapters to build tension, show shock, or document important plot points happening in a rapid succession.
Just write chapters however long they naturally are. That's fine, don't worry about it. As long as they have a natural flow through from beginning to end. Even if they are really obnoxiously long it's not a problem as long it makes logical sense. And yeah, you should be actively looking for those places to split if you get up to 5k, but don't beat yourself up. It's more important that stuff fits together in a way that makes sense than adhering to rigid ideas about chapter length. Even people who read a chapter before bed would rather get to a natural exit point than left hanging. That said - I really don't like the single page chapter stuff that others have talked about. Absolutely hate it. A printed page is like 300 words. If something isn't worth spending even that amount of words writing about you then don't need it. It's just a gimmick and maybe that'll work if you're writing a comedy/satire (like - Chapter 19: Whisky. Chapter 20: Vomit. Chapter 21: Blackout, Chapter 22: Hangover; literally just with one word in each chapter with blank pages in between) but not in straight fiction. You shouldn't use gimmicks.
