Hi!

          It all depends on the show and what you are trying to accomplish. I designed a set for a show called 'Mutiny' that went from a sitting room scene into a fully rigged ship in one scene change that went very quick and seamless. I have built set pieces that transform into other set pieces quickly. Like the steamer trunk in 'Mutiny' that packed like a trunk but then once on the ship it opened up to become low walls and table ( with a stool inside) for the captains cabin scene. I made a 3 tiered plant shelf that came out of a wall and the plants grew and shrank by using electric car antennas.
       Roll drops are always a great fast scene change tool. Easy to rig and can be utilized in almost any stage setting. I have made sets with rotating walls that the next scene is preset so when the walls turn, the scene is there. Again a simple fix, as long as your crew is quiet.
      If you have a specific show in mind let me know your space and I can come up with ideas. As I tell everyone I work with, Do not limit yourself. Think of what you would ideally like to happen and go from there. Never let your space determine your limits.

Stan