I think you're right that it is difficult to doubt our conclusions and a place of incessant doubt can be a burden too. Finding the balance of trustful skepticism is a journey.
This is why I love when I'm comfortable enough to say "I don't know." It such an empowering statement when you use it right, because it keeps you from building your future on false certainty. But you're right it is a balance. I think we just have to do the best we can with the information we do have and trust that any outcome that comes our way is for the best.
Yes! Being able to say "I don't know" is something I really struggle with. Growing up, it was not a welcomed answered, so I learned to just say something. And in my job, saying "I don't know" is so uncommon that if you say it you get a major side-eye.