Yeah, I've never had an issue with sandbox games in concept, only with them being overly cryptic and obscure to the point of frustration.
Just be straightforward and to the point and - preferably - don't have things that can only happen at one specific time frame on one specific day of the week that can get skipped over by unavoidable automatic events that are completely out of the players control, making the player have to go through an entire in-game week of twiddling their proverbial thumbs to get back to the point where they can progress the quest they were trying to progress in the first place.
Ideally, just don't have a time frame mechanic at all, and just let players pick and choose when to do which events/quests and when to interact with which characters in which order, up until it reaches the "main story" needing to progress, or possibly some characters needing progress with different characters, or something else needing to be done.
But if you're going to have time frames, at least leave it at that, and avoid having days of the week and making events tied to specific days, because then things can get far too annoying with just having to waste in-game time to get to the day you need to do something because there's no quests available for days at a time.
And ALWAYS make events only start when the player chooses to start them (assuming time frames and days are part of the game especially), rather than having them automatically start just because the player entered a location or woke up on a day, or whatever, so they don't end up being dragged past the specific time frame they were waiting for to engage a quest by an event they didn't care about in the slightest.
Sorry, my sandbox rant just kind of exploded out of me there
