Coaches HATE TO SEE IT.
Athletes get visibly uncomfortable.
It takes maturity to handle it correctly.
It's the REST INTERVAL.
Too often we conflate activity with achievement. But when we're training for real speed, real power, or real strength?
The session should be a lot more standing around than working.
Because the prescribed work is to go at 100% - and that takes recovery time.
So rest when the training rx demands it.