Can I change materials in a scene without having to bake everything again?

Kind of a noob question, I know. I’m more of a programmer than a graphic though.

However, I’ve prepared this scene of a bathroom, trying to get the best look possible. I was wondering if I could change materials of a specific surface (i.e. walls, floor) without having to bake everything again, and wait 3 hours for it to finish.

Set the lighting baking to manual by disabling the “Auto” baking in the lighting window (Window->Lighting->Scene tab at the bottom) and you will be able to make any change to the scene and just press “Build” whenever you want the lighting to be baked.