The reason he gives for spending time afterwards is at the end of the month to allow you to review a pattern across all of the bugs you worked on recently. Tha

The reason he gives for spending time afterwards is at the end of the month to allow you to review a pattern across all of the bugs you worked on recently. That's difficult to do with just your memory. Just figuring out and understanding a bug is not enough. His point is to figure out and understand how bugs are manifesting themselves in your system... Slipping through all of your safeguards... showing your lack of control of your code.