The major hole in my game was defending Moscow. Only held it once.
A couple of other oversights like not anticipating amphibious assaults. Particularly one where I could have sacrificed a cruiser to kill a transport and thin the assault but didn’t.
Rules are rules anyway, if you want leniancy, you have to ask for it. This would not be a case where I would be inclined to grant it, mind you. If you moved everything from Hawaii to Carlines but forgot to move a fighter there leaving it prone to attack, then I could see a case of “yea, okay, so you intended to move it but it got lost in the shuffle” fine, generally I’d allow that change (for non-league, non-tournament games, of course.)
The group I play with is very casual, a lot of drinking and joking around. We don’t have a set time for turns, but you can be assured that the longer you take, the more razzing you’re gonna get for taking a long time. So either your quick and decisive or you will be ridiculed to the point of not being able to concentrate.