1.5 Reps Technique

I’ve seen youtube videos of these for a few exercises, and I am trying to find the “bigger picture.” Is the .5 rep done on the concentric or eccentric movement, or does it vary dependng on the exercise? Thanks fo your help!

Squats as an example: Go all the way down, come halfway up, go back down, then all the way back up, but for presses I would press halfway up, come back down and then press all the way up. So I guess it varies or can vary with with the exercise chosen. Or whichever way feels harder to do. Not sure that it matters as the point is to obtain more time under tension.

I use 1.5 reps for some biceps movements and sometimes for calves.