I never say anything (as an FO or previously as a CA) unless it is gonna violate or kill me. My captain called me out when I was not matching ITT. It irritates me when my captains tell me how to fly the airplane, and 99% of the time I let it roll off my shoulders even if they are wrong. This was just so silly that I had to respectfully disagree with him. Although in the end I just set the power the way he wanted it so we didn't have to argue. We got along great the entire trip.

I agree with you 100% though. It is better not to knit-pick because then tempers can flare and a breakdown in CRM could result.