[Aloisius]

Yes indeed I often forget to take it during the weekends. I have no compulsion to take it when my prescription runs out (I often delay going to the doctor to get a refill and go a week without, especially if focus is not absolutely necessary).

I didn't realize this was unusual.

[Produce]

Fair enough, that doesn't sound like an addiction at all. If you're just taking it to improve concentration, you might have luck with a combination of a Vitamin B complex, Piracetam and L-Tyrosine. All are cheap and have no side effects.