I have found that while many of the game's elements are RNG based, the rng itself is deterministic on reload.
What I mean by that is that if you reload a save and select the exact same actions in the same order, you will get the same results 99.9% of the time. If you want to effectively save scum for an event, you need a second unrelated action that you can take once, return to the spot with the option you want to grind (effectively getting yourself a whole new set of rolls to check), then redo again until it happens. Some things, like school events, can still happen in the same order though even with this skip.
I am not complaining by any means as this design means you actually need to puzzle your way out of bad situations (rather than just reloading until fate gives you a break), which nicely fits the theme of the game. However, it is a strat you absolutely need to know about when searching out the games rarer events.