I have this super obscure and specific thing I'm looking for and I'm not very confident something like it already exists.
I have created my own system that accomplishes this, but I'd really like to hear if anyone knows any other systems/algorithms/apps/websites that achieve something similar to what I'm proposing below.
Imagine there are 3 distinct collections of items/objects and a number representing how often each item should be featured by the system on average (in days).
Each collection of items belongs to a different user. Users can have any number of items on the list.
1st user's items XONOTIC 16 STACK_OVERFLOW 4 THE_MATRIX_1999 256 2rd user's items YOUTUBE 2 CARDANO 32 ELON_MUSK 64 THE_DARK_KNIGHT_RISES_2012 512 RUST 64 XONOTIC 4 AREA_51 1024 3rd user's items COREJOURNEY 64 XONOTIC 128 STACK_OVERFLOW 16 MINECRAFT 8 NO_BOILERPLATE 4 Certain items from the user's list are selected and shown to the them each day (respecting the user's numbers which determine how often each item should be selected/featured on average, in days). The items are selected randomly but if multiple users have the same item on their lists (in this example XONOTIC and STACK_OVERFLOW) - those items must be featured to all users who have them on their list on the exact same days. So, if there are 420 users who have WEED on their list of items - WEED should be selected and shown to all 420 of them on the same exact days. The software should achieve this kind of coordination using some kind of algorithm that is deterministic and works offline.
TLDR
I'm looking for ANY website/program/app that achieves ANYTHING even remotely similar to what I'm describing.
I'm essentially describing a reminder system that coordinates global reminders about items users have on their list such that the same items have reminders/are featured on the same days for everyone.
EDIT:
Here's the link to the system I created for this, for anyone interested:
https://github.com/TypicalHog/randevu (I don't want this to come across as me shilling my project, I'm genuinely interested if anything like this already exists)