I used to be on 40 mg, non-XR, every day. I would take one in the morning, one at lunchtime. I would make it all day without my mind wandering. Then, when I heard what they went for street price wise, I started saving them instead of taking them, and selling them. I was getting 3 for each 20 I had. I'd sell them 10 at a time, and I had no worries about customers, I had lots of people looking for them.
A little while after I started selling them, I wondered to myself, why are people wanting these, so I crushed two up and snorted them. I didn't sleep for 28 hours. I started using them more and more, eventually I was up to doing 80-120 mg at one time, and that was horrible, I'd stay up 2 days+ without sleep, lost my appetite, started getting nasty violent mood swings whenever I wasn't high. One night, I did 140, which was the most I ever did, and I was up for 3 days straight. I crashed and felt like total shit, so I decided I would quit taking them. That was a massive mistake as well. I had withdrawal from them for about 2 weeks, nauseous all the time, headaches, sweats, etc. I've been clean from them for about 5 years, and I will never touch them again.
If you are using it for ADHD, use only what you are prescribed, and if it's not working, talk to your doctor first. Self-medicating will get you nowhere other than addicted, they are easy to get addicted to. Just be careful, and let your doctor know if you start having any mood changes or whatnot. One good thing, your appetite won't be as strong, and you'll still be doing the same things as normal. It's a good way to keep weight in check or to even lose weight (I lost about 20 lbs when I was on the Dr. dose, and close to 40 when I started using recreationally).
Kef