That's some really, REALLY bad advice. If you've truly done that many clutches, I fail to realize why you still give this advice?? Perhaps most of them were done on underpowered cars such as slower v8's and 4 cylinder cars.
HOWEVER,
a brand new clutch disc has surface irregularites on it. It is not 100% flat, and does not mate up with the fresh flywheel right away. For this reason, even when the pressure plate is fully clamped, some areas of the disc are not contacting the flywheel 100%. In a stock mustang, you'll likely not have an issue that's "noticable" however the more power you get, the more obvious it becomes.
I recently helped a fellow stang netter who had a blower on his car, dropped in a fresh spec stage 2, launched it, and the clutch slipped right away, twice.
It's your call what you do, but it takes a good 500 miles of mostly stop and go type driving to mate that disc in 100% with the flywheel. Your clutch could be slipping even a very small amount if you overthrottle it. the last thing a hard launch is going to do is help it seat properly. A hard launch(or heavy throttle even after the clutch is engaged) is going to slip the disc, and when that happens, it glazes, period.
any advice to the contrary is pure ignorance. If you've taken all that time to put the clutch in, do yourself a favor and break it in properly.