Yes, the oil in HPOP system does not drain out when you empty the sump. Some (retentive) guys suction out the HPOP reservoir when changing the oil in a 7.3l.I've read on forums the 7.3 Powerstoke holds about 2 quarts of residual oil.
Oil changes are 15 quarts.
Residual oil during changes is pretty much a non-issue in my opinion.