I journal to process thoughts, feelings, and problems, so I often go back to try to help me "figure things out." It's a double-edge sword sort of situation. Like it really lays bare the fact that certain problems I've made zero progress on over the years, but on the other hand, it's helps me realize other places where I've made way more progress than I would have thought.
If you've ever seen the Black Mirror episode where they're able to record their memories and play them back, it can be a little like that. An argument with the wife? I can pull back every. single. time. she's done "that" before. I think that's probably not good.
Anyway, overall, when I come away from reading past journal entries I tend to feel a lot more calm and humble.
Just the other day my dog lost track of his frisbee in the water. It barely floats so it must be hard for him to see. He swam around in circles for a while looking for it. My wife started cheering when he would swim towards it, then go "oh! no. no. no" when he was swimming away from it. He essentially worked out hotter/colder on the spot in order to find his frisbee.