For a manager, one of the fastest ways to lose trust from your employees is to be inconsistent in how you evaluate them or what they need to deliver.

If they are doing great one week and you can't figure out what they've been doing for three months the next then that's a sign of poor management, not a poor employee.

Conversely, if they are doing terribly one week and then killing it for the quarter the next, then that's a sign of poor management, not an inconsistent employee.

On a similar note, if you communicate an employee needs to deliver something for a quarter with no other time restrictions, you don't get to then turn around and say "and we need to see this completely done in one week" when you are 3 weeks into the quarter unless that deadline was discussed specifically ahead of time.