If a tobacco is not a vicious tongue-biter, I'll give it a few chances, then jar it up and revisit every few months. If after a while it's still not working out, I will try adding in some other tobaccos to bring it into an agreeable range of flavors. If the tobacco is a tongue-biter but otherwise tastes okay, I'll introduce some orientals and/or non-bitey burley and that has worked pretty well. Hell, I even fixed Mixture 79 by adding Middleton Apple 50/50 and was able to finish it off (won't buy either again though).

I like to experiment, so I see opportunities in the tobacco blends that fail to win my approval, and I learn about the blender's craft in the process.