I didnt use a controller for years, I bought some about a year ago but I always used them on cal 99 and flow 99. Any less and it seemed pointless as the flow wasnt great.
Anyway It must have been the setup in my van that was causing a poor flow, either pumps were past it or they were too high because I got a new pump at the weekend and installed the controller in my truck and it was much better.
Yesterday I used the settings for pretty much the first time ever, mainly because I was running out of water having a smaller tank. The cal function I found particularly useful because turning it down there was no pressure washer effect on opening the univalve. I managed to make my 500l tank last all day, im convinced I would have run out using my normal full whack approach. Also I got back with my batt voltage reading 12.5v. Usually the battery is down in the 11s or even 10s after a hard day with no controller. Probably why I went through 1 or 2 battery's a year. I'll be sticking with a controller form now on.