The thirst of one who seeks erudition must be slaked....

I can offer only a mere a sip....
I think Dave's point about the influence of piston at TDC must be related to a specific engine layout.
A single - or 360 twin - with white metal big end bearings would maybe provide more resistance with the journals higher up as the pressure head from oil tank to the journal oil feed holes is then at the minimum so that certainly makes sense theoretically. In practice? Not sure.
For roller big end engines I doubt it would make much difference (and my M21s are them wot wet sumps worst!)
Ignition on won't make any difference (unless there's a solenoid valve in the oil feed line activated by the igniiton) but even then you wouldn't leave the ignition on long enough without the engine running for it to wet sump - except by accident which would likely result in a flat battery and likely a rather overheated coil(s)....
Cheers,
Bernie