This was by far the worst part of commuting to reserve for me. There was about a five hour window every evening where if I got exactly 12 hours notice for a trip the next day I would have been stuck with no flight options. Luckily I lived within driving distance of base, but it would have been a brutal drive and I dreaded having to make it.
Thankfully I never needed to drive it because the one and only time that I got an assignment like this I was already in base so I just went to the hotel. But this is definitely the one big shortcoming of long call reserve and it forces commuters to make a very difficult choice.