Of course it isn't an exact science, maybe not even a science at all.
I like to think of it this way.
Think of your mind like an iterative non-linear system with thousands upon thousands of inputs.
It operates completely by cause and effect, but because it's non-linear, that doesn't mean it's easy to figure out how it got stuck in a loop.
>In the mathematical field of dynamical systems, an attractor is a set of numerical values toward which a system tends to evolve, for a wide variety of starting conditions of the system. System values that get close enough to the attractor values remain close even if slightly disturbed.[1]
Sometimes when our mind gets stuck, the efforts on our part to get out aren't enough to get us unstuck.
Psychologists or psychiatrists are people who are familiar with some of these mental paths and how it can lead people to become stuck.
They are also familiar with some of the paths that lead to an exit from those undesirable states.
They are attempting to deal with such a complex system, that I don't think it's fair to hold them to the same standard as the so called 'hard sciences.'
For another perspective on the problem of 'getting stuck', from a Buddhist point of view (which is also based on cause and effect) see [2].
[1] https://en.wikipedia.org/wiki/Attractor
[2] https://www.dhammatalks.org/books/KarmaOfQuestions/Section00...