Your players will want to do things that you would never think of. You cannot be prepared for everything
God can they ever. I am constantly doing a trick of smoke-and-mirrors, moving a shop or dungeon I designed that the PCs didn't play to a new location so it's not wasted.
That is actually a very good tip. That place we created for the other city, can be here because we need it now, and nobody will know 😄😄
Absolutely! I do (or did, it's been like 8 months since I added a post) a blog all about worldbuilding for TTRPGs and part of it focuses on how we can maximize the things we make.
If you're interested, the whole collection is here (note that the early posts need to be redone as I didn't have a good idea what my goal was at that point)
https://peakd.com/ccc/oblivioncubed/worldbuildingwednesdays-collection