When we hired non-seasonal TMs we hired them with the intention of keeping them. He hire seasonal with very little intention on keeping them past January 1st. As a regular TM, you'll need documentation within your 90 days showing you aren't doing well. Avoid being late, calling out, no call no shows, and performance coachings.
So the short answers to your questions: 100% of those that don't F it up and biggest reasons include attendance issues, performance issues, stealing, telling a guest to go F themselves, and other egregious actions.