I did a track day at Combe when I first got my 350 with some mates, one also had a 350. Me and my mate were on pretty even terms, halfway through the day his pedal was falling to the floor after a session, mine was fine. We were both running the same std set up. The only conclusion was, either his fluid was shot, or it was something to do with his driving style. Nothing else was different, same set up, same day, same number of sessions etc