Stretching between sets can reduce power and strength output but is included to improve movement quality and reduce muscle tightness.

“if you look at the research stretching in between sets will reduce power and strength output it's pretty well established at this point but you're not optimizing for strength I noticed you liked a lot of those movements in your program so I wanted to keep a lot of those things in there move quality it also reduces tightness so when you load a muscle and load a muscle it can kind of lock down a little bit I like to lock it down open it up lock it down open it back up so it is suboptimal for strength but given the exchange of your goals and risk ratio this is the best play by far”