Choose random Items for gacha every specipic hours

Sorry, this is already my 3rd question on this topic.
But no one answered, so I guess I didn’t understand the question for you guys, so I brought some more examples.

first, this is my question.
i want random values generated randomly in specific times.

these are my solutions i thought but not effective.


Making random value from every server and saving them so make last generated value be selected probably work but it’s not practical. and slow.
Algorithms that make values ​​according to the date would be nice too, but I don’t know how to do that.
Setting main server to make random value must be cool but if the server becomes slow, every servers will get disadvantage.


these all games below are generating random items in specific times.
like characters, guns, musics.
moreover, same in all clients, all servers.

It’s been done before,

Even if it doesn’t work for you or is not exactly what you want, you gotta say what you tried out or what piece doesn’t match your goals in detail.