2012 Sightseer slides, do they all need to be opened?

Having spent a fair number of nights boondocking in rest areas, Walmart's, Casino's, and the such in our Winnebago Suncruiser 37F, I would say "no", you don't have to extend all three slides if you don't need to. We often only deploy the bedroom slide, or 2 out of the 3 especially if parking is tight. Have never had a balance issue even if we just put out the full wall slide.