What to do with unused cooked plastic?

Do you mix a large batch then save the balance for another shoot.?
Do you try to just mix up what will be used for current project?

I mix and use enough for my current task. The scraps are saved to remelt. This saves me on plastic and also I do not have a ton of scrap to label and store.

I make all small batches unless I have to make several injections of one color. The largest amount I make is a cup. If I have plastic left over that is clear and clean with no signs of turning I let it cool then bag it up in a zip-lock. I save a lot of this for practice runs on new techneques I want to try. Using second hand plastic is cheaper than new plastic for trial and error.

I start making pearl first do my runs then if i notice a color change my scrap get turned into pearl chartreuse and I make a few runs then when that starts to change I make black

Depends on if I'm shooting a large or small cavity mold. Either way in the end I have tubs of remelt plastic waiting to be remelted one day. :)

I usually make 2 cups and run several shots in multiple molds. I save the straps until I have enough for a full run on multi molds again. By doing this I limit the number of reheats. Once it starts to turn I go green, red, or black.

I just make all mine ti make black.