I've found the rock bottom to be addictive because the only way is up

I know what you mean.

It is often (but not always) when I hit rock bottom that I make a positive change of some kind. And I can sometimes become very unproductive when I am weeks into NoFap.

I think there could be a libido issue here too. Sort of like, when you look at porn, you tap into that libidinal energy (enegy which as a p addict, is often completely blocked (if no natural outlet). Then when you flip the switch, that energy comes all at once and with it can come motivation to get things done, to improve this or that and reach certain goals.

I have tried manipulating the p cycle so that I can ride on that motivational/creative energy for longer, but it is risky and once the relapse reaches a certain point of severity (which it always does despite my best effort) things go too far and instead of feeling motivated, I can quickly end up numbed out, gormless and exhausted.

As you say, I think it takes time to change this, so that the normal NoFap state has some integration of healthy libidinal energy.