How full should a 15kg dryer in a laundromat ideally be?

And do the small pieces get smaller with every visit there?

Here, 15 minutes costs €2.30, while 30 minutes costs twice as much. Which is better? Is it better to use two machines, perhaps for 15 minutes, or one for 30 minutes? Which is better for your wallet or for the laundry?

You can adjust the temperature from 20 to 80 degrees Celsius in 20-degree increments. I'm not sure what the best setting is?

sry there are more like 4 questions lol thanks for every answer^^