I think I did it once, and found it kind of long. I should stretch more than I do, but once I'm done, I want to be DONE! I had been doing my abs at the end of my STS days so I was about up on time, and another 15 mins wasn't going to fit it. When I got to the longer Meso 3 discs, I moved my abs to my cardio days, in the interest of time. I think I next time I do STS, I will keep abs on cardio days, and make sure I get the extended stretch in on my STS days. I know I need it, I know its good for me, and that will keep me in the timeframe I need to be in.
Nan