It's not binary. As someone with at times very severe executive dysfunction there's still moments of clarity that the line of reasoning isn't going anywhere and any of the actions I've thought of is better than none. Just like when depressed it's about taking those moments of slight strength and do something, anything, to try to lift your self up even if just a normally small thing like getting out of bed.

Statements like this can be true while we still accept and are forgiving of the fact that as humans and individuals we all have limitations and struggles. We can realize that in part we are victims of our situations without letting it devalue our sense of self, in to victims without agency. Because that more than anything will let those small moments of clarity and strength go to waste and prolong and deepen our struggle.

You can train your self to not overthink as much and medical interventions can help if for example adhd is involved. It's about the ability to choose where to put your energy and what trains of thought you'd be better off just leaving and just throwing the ticket in the trash.

Now if it's overthinking or not is subjective. Does pursuing the line of reasoning in question distract you from more important things? Does it hurt you without leading anywhere? Has your exploration gone so far that you've lost perspective? Is the solution you have good enough and any further improvements you might find is not worth your time? Are you working on too little data so even if the reasoning and assumptions are good in the end it's still not much better than a guess?