Hey there! With a pregenerated and shared overworld it becomes quite a task to find rare spawns like unclaimed Astral Temples ore specific ores. Also Pack/Mod Updates that add to world gen will never be found. For that reason I'd suggest adding another overworld dimension, that is reset every week or two - not for building, just for farming these rare spawns.
Heyo, as much I would like to do that, it will just lead to world gen lag every week as people explore that dimension. What I will probably do after the next pack update is to instead increase the size of the world border.