Why is the window displayed once instead of three?

Question

Python

Hello, I can not figure out one laboratory work on metrology. I need to measure the display speed of a square in a window. I run the test in a loop, but the window appears on the screen only once, but the timer passes and I get the execution time of each of the iterations. What could be the reason for this and can I be sure that the calculations are correct?

Answer 1

You would attach the code, the help process would go faster.