When to predetermine A* searches?

So I'm trying to broaden my RBLX LUA knowledge by trying to create the pathfinding a game called Territory Conquest on roblox has.

I started looking into the A* search algorithm. One of the traits I've heard referenced a couple times is with idle waypoints people can predetermine paths. I would love to do something like this, but I'm not sure if I would be able to predetermine all paths or if I should calculate them as necessary.

Does anybody know if I can predetermine paths when the start position and goal waypoints are changing, but all the waypoints always stay in the same place?