As I've almost always seemed to notice, no one is ever around very long for impromptu testing. It's annoying to try and get information when your map is the 5th one down, and won't be tested until 2 hours later. Given that the circumstances are that no one rtv's or rounds end quickly. Impromptus should be quicker gameday's really. They're not really there to give you full feedback, but just enough to fix issues. 15 minutes would be long enough for players to get feedback and playtime in, while keeping players interested on the next map and keeping the running time from dragging. Not so often will people still be playing after about 3 or 4 maps. And by the 5th timeslot, a lot, if not all people are gone. Ruining feedback for those who need it, but are at the very bottom of the list.