What are "touch-up sets", and are they really important?

Question

Jeff is a good guy, but sometimes I just don't get what he's saying. What are "touch-up sets", and are they really important? Why? I struggle to understand even the first sentence

With a touchup set we’re trying to overreach with 10% of what we’re going to do in our first working set, to our five-rep max. What we do is a box squat. The box squat will allow us to get down there, to feel the safety, to have the confidence that we have a bottom point. It will give us that biofeedback to know ‘that’s what I’m heading for’. Give it a one or two rep touch, come back up, then start your working sets. What does that do, neurologically? That overreach allows us to feel more ready and able to attack our working sets with a lighter weight. This, what would normally be our heavier weight, has now become lighter by the performance of that one set. Neurologically, it’s a powerful tool.

Answer 1

The widely used term I've heard for this is an "overwarm single", as in warming up past the working set weight with a single rep set. If they're done for a double then obviously the term would have to change :)

This has mental benefits similar to supermaximal walk-outs for squats, where the lifter loads the bar beyond what they could squat and only sets up for a rep they don't actually do, before putting the bar back. These are used to get comfortable with the sensation of a very heavy bar, so it doesn't surprise or intimidate the lifter.

Overwarm singles may also help through post-activation potentiation. That is, doing a heavy rep signals to and prepares the body to perform better (more explosively, recruiting more available strength) on lighter reps.

The part where he uses a box squat to warm up for a non-box squat is new to me. Maybe it works.