pd or common rail engines both have lift pumps to deliver fuel up to the engine bay, once there the pd has another delivery pump which will create adequit prssure to start but may take a while.
Cr engines have another electronic fuel pump in the engine bay which delivers fuel to the high pressure pump, they can take alot of cranking and you normally end up with the eml or coil light flashing when the engine starts, it'll go off once you do a restart.
cycling the key will do no harm and will
help to pressurise the system before the high pressure components.