I need to replace my front brake pads on the W210 M104. Question is, should the rotors be machined at the same time??

I've had conflicting information my different sources. One was from the dealership that says no, the rotors are never machined. They are either good enough to keep going or they are replaced.
Other forum members have mentioned that they get the rotors machined at every other pad change and replaced at every 2nd change. Who is right?

I'm afraid that if the rotors machining them may allow them to warp faster in the future. Is this possible?

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W210 M104.995 Color 339/205
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