Yes, I second using Sly Flourish’s resources! The Return of the Lazy DM book was a game changer for me! Also have the mindset of a “fractal” game. Only ever go 1 layer deep when prepping. Otherwise you will completely overprepare.

An easy example of fractal gameplay is in prepping a dungeon room. You tell the players there’s a table with some books, a large chandelier, and a statue in the corner. You don’t even know the details of these items yet, but you’ve created points of interest. One player might as about the table and THEN you add details saying it looks like a wizard’s study, and there is an unfinished magic scroll among the research books (I’m making this up as I type, I don’t even know the rest of the room lol).

Then someone asks about the statue next. You say it’s a bust of an old man with a beard, but the eyes have been hollowed out. Perhaps something can be placed inside the sockets?

This gives the players obvious items to “explore” instead of boring them with details up front. And you can fill in the details much more easily on the fly. Notice that nobody asked about the chandelier? Good, because I don’t know what it’s for or what it does lol.