There’s a lot of information out there about how to belay, and sure, the mechanics of holding a rope are important. Project belaying is another cup of tea entirely, an art that walks the line between self-sacrifice and domination over your climber partner. A good project belayer will say only, “Excuse me—can you hold on…
https://climbingzine.com/project-belayers-the-real-heroes-at-the-crag-by-tanager/