While I'm sure the timed squats had a positive influence on our aerobic conditioning, the unexpected plus from doing the routine was the way it affected our mental states. Prior to embarking on this program, we always took five or more minutes between our heavy sets. Timed squats taught us that we didn't need much rest. ...that understanding of what the body can withstand under dire stress gave us a tremendous boost of confidence on the lifting platform. If we got rushed between attempts, it no longer mattered. It also helped us move through our regular sessions at a much faster pace, which enabled us to do more work in less time.
From Time To Squat by Bill Starr
A few years ago, I was training for a birthday goal of squatting 225 pounds x my age. As was the case with me frequently back then, I ended up hurting myself before the attempt because I couldn't back off even when I knew I had already done more than enough. Anywho, in preparation for the high-rep challenge, I tried a lot of things, including this timed squat session which was quite demanding.