izzdann- i used to be able to roll like crazy and each time i have had to up my amount of pills eaten to get to that same level. BUT- the last two times i have tried to roll (spaced out 3 months) i felt some effects for possibly 30 minutes but most of the time i didnt get that feeling i used to (you know, walking on air, etc). i know it isnt my tolerance because im a pretty small person and the last time i attempted to roll i was in a good mood (that day, anyway) and even 5 1/2 pills in a few hours didnt work for me. my friend who took the same pills, rolled balls.
anyway, my opinion is that 1) e loses its magic if you do too much too fast. this is different for everyone too. but you know yourself best and you know when you are and arent rolling. some people recover more quickly than others. 2) your general life state (stressed, depressed, etc.) can greatly affect your roll.
i have been going through dramatic changes in my life (family issues, academic issues, etc.) and my general level of stress is twice what it used to be. consequently, my rolls have stopped being magical. are you experiencing an unusually high level of stress? sleeping less, eating unhealthily? i have a feeling it isn't something wrong with you, but rather, its your body's way of asking for a little more recovery time.