So only a single powermode is allowed during qually and the whole race. But ERS harvest/deployment schemes can be changed at any time.
What if the electric supercharger mode is coupled to a very agressive ice powermode? Than a team could use allot of e-supercharge mode for the hot lap, race start and overtake. But it switch to a normale more sustainable ERS scheme for normale race laps with very little e-supercharge mode, to preserve engine wear during the race.
Could this be done to extract some single lap speed, without actually changing the power modes?