Ideally I would like to be evaluated both with and without prior knowledge. Evaluations serve both the purpose of official development and official management (assignment, advancement, discipline etc.).
For development it makes sense to know what the expectations are, have the opportunity to let the evaluator know what you are working on and get critique to make same game adjustments. So meeting before the game, at halftime and after the game is helpful.
For officiating quality, unannounced observations are crucial. Officials should officiate each game as if they were observed.
I prefer a verbal and hard copy evaluation. Hard copy evaluations using standard forms promote consistency. For some sample evaluation forms, you can check out
forms .