I prefer 15 mins aswell.
Dunno if any agencies offer them but 1122, luxxxe, and coco offer 30 mins.
as far as independent girls who offer it, I know nicole love (ads not up right now), Lia 1375, brittany natasha 9370, lexi skye 0669, carmen 6467 offer it. theres more too but I cant remember right now.
Theres some girls who will offer 15 mins aswell after you have booked them a couple of times before in my experience. sometimes you just gotta ask, it helps if you ask during a time of day were they are less busy.
I wish more girls offered this, I feel like it used to be commonplace 5 years ago.
Im always looking for more, so if anyone has any other suggestions please update this thread