What's the scale, how are people evaluated against the scale etc
Then a chosen few are told their top tier and can continue to get stocks (assuming the stock hasn't grown since the last time the got stocks, we're owners so growth is all we need. Or assuming the stock hasn't fallen, we're owners so we need to help the trillion dollar company. Or assuming they've not been top tier too many years in a row), and the unlucky few, get put into the pipeline for "unregretted attrition" and are a feather in the managers hat when they're forced out.
Like most do them - poorly.
Managers just pick out some sample behaviors from your year and fit them to whatever rating they feel you deserve. Pretty much the same everywhere, but just dressed up differently from one place tl the next.
I quit a few months later.
For instance, what I consider to be strong signs of leadership skills in junior positions includes: commitment to finishing activities according to expectations, interest in fully understanding task requirements, start making limited autonomous decisions, and initiative to keep stakeholders updated on task progress and any changes in direction.
Our hack for this was just to make the most experienced engineer on a platform do all the performance review stuff that the manager would otherwise do. It puts them out of action for a while, but it's better than the alternative.