[WhyNotHugo]

I've had long periods of my life caffeine-free, and this has given me some interesting (personal) insight into its effects.

After daily consumption, it takes two to three weeks of zero consumption to restore a sane "baseline" where I can operate at the same level of awakeness with no caffeine. Consuming coffee after the third week has a noticeable impact where you can really feel its effect.

Caffeine doesn't make me more focused; it mostly suppresses my tiredness/sleepiness. Being awake does not equate to being more focused.

I don't think that one week is enough to recover sensitivity if I usually consume daily doses.

Generally, I tend to avoid caffeine due to all the other changes in mood / behaviour / sleep. The effects are mostly obvious if you switch to zero consumption for a few months and then take up the habit again.