737 pilot (10 years). Standard procedure is to open the DV window to ensure aircraft is completely depressurised in an emergency situation. You can override slight depressurisation to allow the much larger door to be moved and opened by the cabin crew. This would be done in a reject take-off when the fuselage would be lightly pressurised, or on landing in an emergency situation. The fuselage would be pressurised at 0.18 psi, or about 100' below airport altitude, so overriding it is possible.
Might I suggest those that don't know don't answer!