Baz,
Would you only measure 2 pistons in a 6cly 3.9lt for a customer and give it a clean bill of health?
so follows
Would you only measure 2 rotor faces in a 13B and give it a rubber stamp pass BDC style?
You would measure all pistons and report on each.
Mostly everyone inc me and you would measure all rotor faces and report on each.
Why would we do this? if its only using 2 faces and is only 1.3lt in capacity? Surly by Mazda convention and everyone else's then we are mad and we could have saved money by leaving out one apex seal per rotor (potential saving there!) just as we could leave out 4 pistons in the 6cyl and save weight too
PROBLEM: Engines function and displace volume over the operating cycle and total sum of working chambers. This is how all internal combustion engines work. 2 stroke, 4 stroke and low and behold the Wankel too