Four to five hours very closely resembles "Cold" from a fuel delivery standpoint.
The accumulator is of no use to a "cold" system, it is designed to maintain fuel pressure during the hour to two after shut-off when the heat of the engine will boil fuel waiting in the injectors. No pressure is needed on a cold engine as the pressure rises almost instantly with the fuel pump.
Bosch Master, ASE Master, L1
33 years MB technician