Potion resevoir is so whack

I have to take it out, activate it, put a pot in, and then turn it on.

If I have one dose left it in it's literally pointless as I have to either destroy it, or take a spare pot/resevoir with me

Why not just have it automatically refill any potion effect when switched on, maybe top up every 5 minutes so you lose 1 min of potion time as a cost

Or, maybe just have it drain divine charge like a regular invention gadget