It is useful to think of training on a spectrum from expansion to consolidation. Expansion is attempting something far harder than previous accomplished. Consolidation is mastering something that can already be achieved.
New climbers tend to do all their training in the middle of the spectrum, investing their efforts on routes that are right on the precipice of completion. This optimizes for satisfaction in terms of setting new personal records. It is short-term focussed and progress quickly plateaus.
The pros direct efforts at both ends of the spectrum. These take many guises depending on the school of thought: ARC-ing, active recovery, limit bouldering, “try hard”, “never take”, etc. The main idea is similar though: Mastery is builds a base for further gains and stimulation teases out the gains.
Applying this principle to physical training is not novel, but new climbers are often surprised that it applies to mental training as well. Even disciplines such as visualization, sequencing, and fear control are improved through consolidation and expanstion. Ever sent an unlabeled route, only to find out that it’s way harder than anything else you’ve done? That’s self-perception holding you back. It can be expanded by imagining you’re a Vn+2 climber, and jumping on Vn+2 routes. You might not send any of them, but the act of walking up and starting is enough to erode the self-reinforcing belief that you’re a Vn climber.
More generally, this, as with many other climbing lessons, abstracts well to other parts of life: The idea of expansion and consolidation should be a useful way to organize learning of any sort.