I definitely would do all 4 at the same time otherwise you are going to mess with the front rear braking balance. This will be even worse on track as the pad friction changes with heat this will be an even greater variable on track with higher temps.
Just to say I had an issue with pad transfer on RS14’s creating judder on my old s2 exige with big brake kit. I tried the bedding in process a few times but couldn’t get rid of it. It was fine at road speeds, but every time the brakes got hot on track it came back.
Somebody recommended the following and it worked for me… soak the dis