Peter de Groot, with C41 processing, the time is about the shortest time of any film processing, as such, you should aim to be as accurate as possible with the developer time, along with the temperature.
Even a little more time can make quite a difference, as can a little less. To push process C41 one stop, you only add 30 seconds, so you can see that if you somehow add 15 seconds to the developing stage, you are effectively push processing ½ a stop.
To ensure that my C41 development time is as accurate as possible, I use a stop bath of 2% Acetic acid solution, then I continue with the bleach step.
I would suggest that you don't run a stabiliser solution through rotary processing, you will end up with very hard to clean tanks and reels.
In fact for C41 stabiliser I take the film off the reel and drop it in curled up, or in the case of sheet film, into a tray, using gloved hands to carefully agitate and then pull out to hang up.
C41 is very easy.