Repertory is often described as a virtue. It is mostly a logistics problem, and this is what it looks like.
The turnaround
A matinée of the Beggar’s Opera comes down at 16:35. The Weir Keeper goes up the following evening at 19:30. In between, the band’s nine chairs, nine stands and the harpsichord come off; the 1728 floorcloth comes up; the dam face flies in and is checked at three heights; the water line is re-dressed because it dries differently every time; and the whole rig is re-focused for a state that has to coexist on the same bars as the state it just replaced.
Why the three plays are lit off one rig
Because there is one rig. Every lantern that moves for one play has to move back for the next, so the three lighting designs were plotted together, in one room, before any of them was hung. That is a constraint most theatres never have to work under, and it is why the three plays in a Lanthorn rotation tend to look like they know about each other.