Attenuation, body, foam, lauterability.
It's typically applied to german lager buts i've adopted it for all beers and it's been a game changer for me. There is a level of tweaking to it though.
Another thing i recommend with it is to take wort gravity samples at the end of each step so you know how much extract you've obtained.
Usually you can get about 85-90% after ~30 minutes of beta, another 10% from alpha, and the last 5% from mashout. Give or take a little. Each grain can be a little different.