Does ammunition ever "go bad"?

Question

I own a 9mm and love using it for target practice. I use Winchester ammo for practice, but I use Cor-bon JHP for personal protection when I carry. The practice ammo costs about $20 for 100 while the JHP bullets cost $20 for about 20 so naturally I don't want to use the expensive JHP bullets for target practice. I go through the cheap ammo quickly so I don't have to worry about it "going bad" but I never use the JHP bullets because how often do you have to shoot someone? So my question is, is it ok to just keep the JHP bullets for a long time until I need them (if I ever do) or should I replace them ever so often?