Generally, if I have to pull a massive effort (an all-nighter), which only happens a few times a year, I start with writing some tests that will keep the bug in

Generally, if I have to pull a massive effort (an all-nighter), which only happens a few times a year, I start with writing some tests that will keep the bug introduction problem to a minimum. It works, though the frustration level is high. But better catch the bugs early than late.