Is It a Real Pattern: Monday's Server

A colleague from the ops team says: "The server is slow every Monday. Last month too, response-lag alerts came in twice on Mondays. Let's stop deploying on Monday mornings from now on." When you check the actual records, over the last 8 weeks there were 5 response-lag alerts total: Monday 2, Wednesday 1, Thursday 1, Friday 1.

Design a way to tell whether 'the server is slow every Monday' is a real pattern or coincidence. Your answer must include (1) how the data should look if this pattern is real versus if it's coincidence, (2) what and how much more you'd collect or observe, and (3) what evidence would refute this pattern.