There's zero/zip/nada reason to think the minimum thickness specification isn't the same for OE and aftermarket rotors. It has as much to do with maximum extension of caliper pistons as anything.

It's a silly question to ask if it's needed every time, every other time, or whatever. It's needed when the rotors are at or below minimum thickness. Consideration should also to be given as to whether they will wear past minimum thickness during the lifetime of the new pads about to be installed.

Skimping on any maintenance is foolish and skimping on brake maintenance about the dumbest of all.

To expect a professional service facility to play games with your safety--even if you requrest it--is to miss the point.

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Kent Christensen
Albuquerque
'07 GL320CDI, '10 CL550. '01 Porsche Boxster
Two BMW motorcycles