Depends on several factors
How much time I had invested (how many tries so far?) The more tries, the longer the frustration lasts.
What kind of mood I was in to start with. I try not to work on anything when I am in a crappy mood, but that limits me to about 12 minutes a week...
How well I thought I was doing just before everything went south. If I have been working on something for a long while and think its looking good, then discover otherwise, its much worse than if I were to notice early on see the corrections I need to make.
I have been working on a scratchbuilt/kitbash 1/16 WWII US Marine for some time now. For a while he languished in the pile, then I got back to doing him. Twice I thought I was to the point to prime him and start painting, only to find something I really didn't like (both times I hated the left arm I had used from the parts box, both of them I tried). Both times I actually threw him across the room and busted him into pieces. Fortunately both times all the parts were easily found and reassembled. Finally I decided just to sculpt a new arm. Each time I wrote him off entirely, but by the next day there I was, collecting the pieces and going back to work. Once again I am to the priming/painting stage, and if this time it goes bad, I am taking him outside, dousing him with gasoline, and ending it once and for all! A.D.D., bipolar and in need of anger management is not a good recipe for success!