I wear pretty much the same make-up and lingerie for my photos as I do my bookings, and that takes around 15 minutes to put on if I'm already showered, my hair takes 2 minutes to brush or put in a clip.
What I found with shorter appointments either 30 minutes or the occasional trial quickie was that as already posted the amount of faffing, people being late, requiring numerous texts, chopping, changing, not willing to make a phone call, then pushing the time and resisting leaving on time was so high it made them just not worth the hassle. Given that the basis and majority of my business is 1 hour plus appointments it didn't make sense to carry on with something that involved more hassle and less return (the few shorter appointments were getting in the way of the longer bookings), so I made my minimum booking 45 minutes which works very well.
Some SPs do make quickies a speciality and I assume that they have a system in place for 15 minute appointments.