I rarely pass up a buck I would be happy with killing the last day. Sometimes I kill that buck the first day of the hunt sometimes not. It all depends on where I'm hunting and the expectations for the area. For instance I hunted eastern MT a few years ago and I can't remember how many bucks I/we passed up on that trip, we saw way more than usual. I looked at probably 100-120 deer a day and in 5 days saw one buck that I was willing to put my tag on. Never found him again though, and went home empty handed.
Does passing on spikes and forkies count, or are we talking about deer we kick ourselves for not killing? I'd say on an average week long deer hunt, I'll pass on probaly 10-20 'buck" deer that are in a position where they are killable, sometimes more sometimes less. If I'm hunting in MT at the "feed lot" for whitetails, it could be 6-8+ bucks a morning, sometimes more.
I can only think of two bucks I passed on and killed later on in the season. One I passed on 3 times thinking he wasn't quite big enough. I learned my lesson though, when a whitetail is 250+ on the hoof his rack tends to look a little smaller than it is. Just wider than the ears means really means 20" inside not 17".

Another one I passed on the first day of the hunt, had him at about 75 yards and dry fired on him... Tried to talk my buddy into shooting him, but he wanted to kill a muley later on in the week. Second to the last day of the hunt I talked him into shooting that same deer and he missed 2 or 3 times, so not one to let a nice deer get away, I piled him up. I was happy and if we weren't specifically going muledeer hunting I would have killed him the first day.
I've never had a 'premium' LE tag though. I should pull one next year and we'll see how much talk I really am. I'm more than willing to eat tag soup if I can't find a book sized deer. I've been saying for years that I won't shoot an elk unless he's a 6pt. Hasn't worked out quite like that yet. LOL