With each significant memory, either positive or negative, is associated an attendant charge of emotion or energy - this is nothing new, and Freud was putting the meat on the bones of similar theories over a century ago.
I am aware now that the magnitude of such charges is never permanently reducible to nothing, even when cues to a specific memory are presented repeatedly.
I haven't drawn the graph of the decline, but the charge of energy does fall away with the number of repetitions, dwindling to somewhere just above zero at the nth presentation of the cue.
The withdrawal of the stimulus allows the energy charge to replenish slightly. Without any scientific rigour, I tentatively state that the charge replenishes more slowly than it drains: after n repetitions, and n equivalent rest-units, the cathexis would be more drained than before the presentation of the first stimulus.
This idea gives us the opposite of learning - where increased exposure to something results in enhanced recollection; and its withdrawal weakens powers of recall.
Strong emotions, then, would seem to be a hindrance to recollection. It is best to engage in learning with a cool head, and avoiding the strong, familiar scent of memories (I don't best know how this can be done) which encourages the perfidious bubble of cathexis to inflate massively, and obscure everything.
