proc saving is useful but you have to know when to do it, for instance a good time to save a firestarter is right before thermonic beam from darnus (jump -> iron chariot -> beam) if you get a proc a cast or two before a crucial time to move then its smart to hang on to it as statistically you wont get another on your next cast. It's more important to keep the gcd spinning when you can. But no, don't hold a p roc for 3 or more gcds.