My Jobo ATL processor can't be programmed to presoak with a max amount of tempered water while the amount of chemical is programmed differently at a less volume. This was where my problems began. I wanted to develop at least two 220 rolls at a time with a minimum amount of chemicals. Prewarm on a Jobo ATL never worked for me. I would never try it again and waste any more of my films/images.
I do not have accurately tempered prewash water supply. I can't use a prewash cycle which would give me plenty of volume of presoak water before the development cycle. So I use the tempered supply bottles for presoak. It turned out that I do need two steps of presoak to get the films close enough to 100 degree before the developer is poured into the tank.
For E6 I will need to set up a tempered water tank to supply tempered prewash water. Or I will really need to figure out how to prwarm the film and tank without presoak. I tried once to develop 4 135/36 rolls of Velvia 50 with prewarm. I got miserable results.