I wonder how much difference it makes? I know my truck has 2 large places that never drain. I haven't seen as much of the insides of my car engine, but I am sure it holds some that never drains. I have even seen figures on some engines where the total oil capacity is greater than what it takes for an oil change. Draining cold, it has had all the time to run down to the the pan as a hot change, plus the time to cool down. The cold oil will drag solids in the pan out too.
I think the worst thing would be the engine recently run to circulate oil to the top, but not enough to warm it up for a fast drain. Don't run a cold engine just long enough to get it up on a ramp.
Of course, the cartridge filter in my Ecotec allows oil changes flat on the floor. I never did need ramps with my truck.
In the past, I have been anal enough to drain hot and let set overnight. Considering how few engines wear out before the rest of the car falls apart, why worry?