It will depend. Tolerance to caffeine is quite unique in the sense that it isn't a mere 'increase the dose to get the same effects' reaction. Caffeine can act drastically different in somebody known as caffeine 'naive' (infrequent using) and caffeine 'tolerant' (frequent using) persons.
Caffeine has a wide variety of effects in the body. Mechanistically, some of the effects are direct (such as Caffeine acting as an Adenosine Antagonist, the molecule literally blocks the receptor) and others are indirect (any effects on dopamine are 'downstream' of the reaction with adenosine, like the latter aspects of a Domino cascade). When tolerance develops to caffeine
If consuming caffeine for disease prevention, it is not required for risk reduction of Parkinson's Disease nor is it required for risk reduction of Type II Diabetes. Actually, it is probably recommended to keep chronic Coffee or tea (not just caffeine) intake for diabetes risk reduction, as the negative effects on glucose metabolism by caffeine are reduced with tolerance.
Benefits on endurance exercise, typically increasing the time to exhaustion during cardiovascular exercise, do not seem to be reduced with time.
If using caffeine to combat headaches (by reducing cerebral blood flow), cycling is not needed as the degree of blood pressure reduction does not differ between naive and tolerant users.
Usually, reactions mediated by adrenaline are those that it is recommended to cycle caffeine. The effects of adrenaline from caffeine are reduced during tolerance, but they do not fully disappear. This is due in part to a reduced secretion of adrenaline in response to caffeine, but also due to a reduced amount of adrenergic receptors in a state of caffeine tolerance.
Reactions that are mediated by adrenaline are increased focus, fat burning, and appetite suppression. 'Increased Focus' should not be confused with wakefullness, which is an adenosine receptor reaction and not attenuated with tolerance.
It should also be noted that the adverse effects of adrenaline, the increases in blood pressure and heart rate, will be preserved if one successfully cycles to keep Caffeine's adrenergic effects pristine.
Cycling is needed for anything pertaining to dopamine signalling in the striatum. When tolerance develops with prolonged caffeine usage, these effects quite literally disappear. It is known as an 'insurmountable' tolerance, in which rather than a dose-response curve shifting to the right it instead gets flattened.
The effects that are mediated via dopaminergic signalling are locomotion (have caffeine, start to run around in circles) and euphoria. Euphoria should not be confused with a mere 'greater well being', which can still happen
(Common phrases used by users for this page include proper caffeine cycle, naive caffeine consumers response to caffeine, how long to cycle off caffeine, do caffeine tolerances fade, cycling consumption of caffeine, cycle off caffeine)
(Users who contributed to this page include KurtisFrank)