You may well be right for all I know. My point was more that if the master cylinder seals are perished then the slave cylinder seals will also be in poor condition and liable to let go in the near future, so it makes sense to my mind to do both at the same time. I have always believed that if you do a job properly, you only do it once; whereas if you do a job poorly it will have to be done again.
Anyway that's a decision for Mohame to make. We have presented him with two options to choose from, both equally valid for different reasons.