Data, not opinions

We all have opinions about how things work. What is or isn't right. How things should be done and so forth.Then there are facts. Data.It's applying the scientific method to things.My friend who has the Mini brake issues was looking to get things fixed. Ok, it's not an issue per se, they're just worn. Worn brakes are not an issue unless you let them wear too much. The typical thing is to replace the rear brake rotors when you do the pads.I look at that and thing "hogwash, they're looking to scam you."This is all well and good. I have an opinion. It's worth the paper it's written on.But then there are specs.The rear brake specs say you're good until they wear down to 8.4mm thick. I measured them at 9.1mm.It's no longer an opinion thing. It's a data thing.