It would have been in the interest of theatre managers and scene keepers to limit the number of side-shutter (wing) changes in a production. Assuming four wing positions, as in my LIF model and in various stage designs by John Webb and Inigo Jones (see the Hall stage),  the total area of the wing scenes would be more than twice that of a backshutter pair. This and the fact that painting wing scenes was a specialised art – especially if the setting required strict optical alignment, as in a scene of perspective – meant that a set of wing scenes was likely to be more expensive and time consuming to paint than a backshutter pair. Moreover, changing the wings in a manual system, as at LIF and most likely Bridges Street, would have required one man per position per side. Synchronizing wing changes with backscene changes must also have been difficult. When we take these factors into account, plus others such as noise and the increased likelihood of mechanical issues, it seems likely that authors would have been encouraged to limit the number of wing changes required in a play to three or less per Act (matching the available grooves in the LIF model, though Jones’s Salmacida Spolia stage has four). This could be achieved by making wing scenes more generic than backscenes. So, a set of tree wings, for example, could be matched to various backscenes depicting forests, woods, groves, gardens and the like; and a set of chamber wings might do for all interior scenes in a play. In these cases, if any specificity or distinction was required, it would be provided by the backscene.