Thief practicing?

I spoke with an Immortal and he asked me to post it on here. I practiced gutshot, and a few things up to 44% to get to third attack. I am still unsure if it is based on total number of special practices you use, or just number of skills you practice per guild, but I wanted to save some practices was my intentions. But the problem occured I am no longer allowed to practice any of thsoe up to 75%. I tried gutshot, and it said You cannot practice gutshot. I think it is a bug that you cannot go back and practice skills you have already surpassed. Thanks for looking into it, And are you able to tell me if it is based on practices or skills? Yaspur.