I’ve noticed a lot of projects doing things like working with 300 x 300 pieces or similar small sections to build interiors even if it is a considerably larger area utilizing the same base materials. Is it better for optimization purposes to say make a room out of 20 pieces rather than 6?
It can be. Re-using meshes in a scene cuts down the calculations needed to run them, so you are better off building things out of smaller bits, rather than using larger, unique pieces.