Last night in my sandbox, the travel-weary PCs approached the village of Bratanis. There was a long building friction there between the Lady Aeschela and her lieutenant, the Weaponmaster Ruggio. I rolled a d6 to see if Ruggio had finally overthrown Aeschela and made himself Lord, 1-3 'yes'. I rolled a 3, and events proceeded from there. I didn't see any need to make the Schrodinger determination prior to the PCs getting there.
Other things may be on a timetable in-world, eg it's known that as the rainy season ends in M3 (it's early M2 now) an undead army of Neo-Nerath will be coming over the mountains to Hara. That will presumably happen unless the PCs or something else big stops it.
In general, stuff immediately around the PCs I'm looking at daily/weekly on a small scale, further away monthly & on a larger scale (eg Hara & the undead army), further still yearly and larger still (what are the Red Reavers of Grimalon up to) and even decadal (how are the Invincible Overlord and Green Emperor doing). This gives reasonable economy of effort - if my game's not set in the CSIO I may only be thinking about the CSIO every year or so of real-time. Most of it can be updated if/when the PCs go there, and yes a lot of it can be used frozen-time, NPC X is the way they are in the book whenever the PCs first meet X. My Karameikos game is 20 years in (1020 AC from 1000 AC start), major NPCs get aged 20 years (and some die of old age) but some I'll just change their backstory to be 20 years younger.
I used to be the sort of GM who generated vast reams of material for its own sake, and eventually found that this was hurting the actual game at the table. Every detail I pre-determine takes away an opportunity to make it differently - and sometimes different would be better, but I can't know what would be best for the game. I don't have infinite inspiration; if fix too much too soon I am destroying possibilities. My current Ghinarian Hills setting is working brilliantly, but only because I detailed one or two locations at a time, over months, as inspiration came to me - and am still doing so. If I had tried to detail everything up front rather than incrementally it would be a much much weaker setting.