Recca Gatsby
LWO
How long would it take you to completely lose your mind? I read that he spent 10,000 years reliving that same day over and over again.
He was stuck in that time loop for about 8 years.
We've pointed out before that, according to the original script, Phil spent 10,000 years repeating the same day, but a lot changed between that version and the finished movie. And the film skips over most of it in a montage, during which Murray's character masters a number of complex skills, taking advantage of all of the extra time.
So in order to determine how many days Phil actually repeats, blogger Wolf Gnards (we hope to dear Jesus that's his real name) started by counting the ones that are shown in the film -- the answer is 36, which frankly doesn't sound that bad. Oh, but we're just getting started. The blogger then took into account lines in the movie that suggest the passage of time. For example, at one point Phil tells Rita that he has been "stabbed, shot, poisoned, frozen, hung, electrocuted, and burned" -- of those, only the electrocution was shown on screen, so, assuming all the others didn't happen at the same time, that brings the minimum total to 42 days.
Gnards then took into account the skills Phil learns throughout the movie: throwing cards was six months (according to the dialogue), robbing a bank was probably a month, playing the piano takes at least three years, ice sculpting is about the same, and learning French probably took about two. Did Phil take on all of these one at a time? Probably, since ice sculpting is pretty difficult to master, and it's not like he's in any rush.
The movie's director, Harold Ramis, actually commented on this theory, saying the estimate seemed too short and declaring that people like Gnards have "way too much time on their hands." Yeah, probably.