In my experience at huge companies, getting a 4 or a 5 is largely a paper-trail formality that managers bestow on people they are grooming for promotion. It's a political gift and a retention mechanism. Everyone else always gets a 3, whether they've been kicking ass or competently coasting.
Systems like these create strong disincentives to focus on job performance above and beyond a certain baseline, and strong incentives to focus on self-promotion, politics, and lobbying for sexy projects and allocations. Especially true when there is a forced curve or stack ranking involved. (Spoiler alert: there is almost always a curve, whether formally mandated by process, or informally expected by leadership.)
Systems like these create strong disincentives to focus on job performance above and beyond a certain baseline, and strong incentives to focus on self-promotion, politics, and lobbying for sexy projects and allocations. Especially true when there is a forced curve or stack ranking involved. (Spoiler alert: there is almost always a curve, whether formally mandated by process, or informally expected by leadership.)