I find that my workouts take a fair bit longer in the 5s (I do 3 sets of 5 for most of my 11 exercises). For the heavy stuff like squats and deads I just rest while my partner takes his turn, but, towards the end of the w/o when I'm onto arms, I try to do calves while my arms are recovering. Speeds things up a a bit.
If the gym was busy it did take me an hour and a half to get through all my sets (esp. if I added a high rep metabolic set here and there too). Whilst taking an hour and a half didn't seem to spoil my progress, it did seem like a long time.
What I am trying to do this cycle is to streamline as much as possible so that there is less waiting time and swapping from station to station. So, for example, I now do standing shoulder presses using the same bar that I've just used for shrugs rather than faffling around with the Smith machine and swapping benches about. It's been a great timesaver and the exercise feels better too.
During the 15s I generally do one (but sometimes two) sets per exercise which takes about 30-40 mins tops. I try to move around as swiftly as possible whilst avoiding throwing up!
During 10s I do 2 sets of everything which usually takes just shy of an hour.
Best thing is to keep your workout to a length that you enjoy and which doesn't leave you feeling too drained so experiment this cycle and see how you get on.