Back in the day, when I was MUCH younger and shot serious IPSC Competition, I would cast continuously. My record is 13,000 match quality bullets over a weekend (I cast, and my two sons pre-melted ingots in an open pot and kept my BP pot filled). Now that I have gotten older and don't shoot as much, I cast one full pot at a time.
I fill the pot with metal (alloying at the same time with all clean metal). I then sit down and cast until the pot is nearly empty (leave an inch or so as I believe that is easier on the pot). I keep that lot of bullets together, sizing and boxing them.
Since I only do one pot at a time, it only takes one to one half hour casting time (after the metal is up to heat). It would not be a particular benefit to me to have the plate. I don't really need a PID, either (although part of me would like to have one
>)). By not adding a lot of cold metal to the pot, my temps stay pretty consistent. I DO add the sprues back in to the pot. However, I don't let them collect too long before returning to the pot (they are still pretty hot so don't change the temps much).
Since I have a two burner hot plate, I have experimented with pre-heating ingots, too. If I were going to more that one pot at a time, pre-heating the ingots minimize melting time for the second full pot. Or, conversely, you could just drop one pre-heated ingot in the pot at a time and keep going...
I pre-heat my molds with a hot plate and have a small manicurists fan to help maintain mold temperature and cool the sprues quickly.
Just a thought or two...
FWIW
Dale53