Surely as a "true professional" you should do them in such a way that you've convinced yourself that the aircraft is ready for flight, regardless of what another pilot thinks?
Personally, if I have another pilot with me, I try to encourage a joint pre-flight. On at least one occassion, another pilot has noticed a problem that I'd missed. I don't consider myself "unprofessional" for having missed the problem, but I would have considered myself unprofessional had I not made use of all the resources (including the other pilot) available to me.
FFF
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