Typically, when the FMS Bridge visual or any of the visuals ar run on 28R, 28L cannot be used due to the close prox.
That's not correct. At SFO both runways often operate in parallel during visual approaches, e.g., while 28R is on the FMS / Quite Bridge visual, aircraft on 27L might be on the Tipp Toe visual (along the ILS 27L localizer).