Well, you shouldn’t need a large amount of variables to keep track of for AI decision making purposes. Something like the example here regarding health, I would use a setBBKey because it’s not constantly moving, it’s a value changing when there is an interaction- so 1 frame usage per change. You would want to use a Service for something that can change constantly, such as distance to the player, and that would just be on the BT. (Unless it’s needed on the blueprint)
I think you can use “Make Literal Name” and pass that into the “Set BB Key” node so you don’t have a big list of BB Key variables, keeping your blueprint neater and cutting down on clutter. 