I think there is a fine line. You can easily go too high, but if you can't ride in the proper attack standing position, then the bars are too short.
Being 6'4" I find many stock bikes are too short, but usually 1/2" or so is plenty. My XRR has 1.5" risers with CR highs, but they are oldschool bars in crotch bikes. Don't get me wrong, some people rip like that but I feel I'm in a poor position and lacking leverage and strength while standing. Also awkward.
My KTM I put 1/2 or less on it with stock bars and it felt great. You do notice the risers on hill climbs till you get used to it. Too high and you find yourself fighting the bars in chest feeling on climbs. It's amazing how little adds up to so much!
I like to try as many bikes as I can to compare fitment and see what I like and what I don't. Bar position is always the biggest (beside lever positions) I notice right away.