Oh, and I personally have never found any benefit to stretching between working sets.
Whether stretching prior, or performing warm-up sets, by the time I get into my work sets, I’m as limber as I’m going to get.
I mean, if I performed an additional 30-minutes of solid stretching, I may get a little looser, but an extra 10 seconds between sets by that point in my workout will yield negligible (at best) benefit.