Robert Chambers wrote:
It may depend on the field, but if you have an IFR arrival inbound on an
ILS approach, and an IFR departure waiting to take to the skies, the guy
on the ground is not going to be released.

No reason not to if there is a tower.


At larger airports where
they have more runways or larger distances separating incoming from
outgoing they can squeeze the timing a bit.

The number of runways or their spacing is irrelavant.