[cameronh90]

I think my average level of useful focus is just simply higher with caffeine. I was off it for three years, which is well beyond the time it would take to lose any tolerance, but never really reverted back to the same level of focus that I get with caffeine.

I'm not sure my overall focus over time is higher with caffeine, but it does allow me to nudge more of it into the useful part of my day. However I'm a fast metaboliser of caffeine, and it doesn't impact my sleep at all, so could be that there's a genetic component to one's experience here.