I have a SnapOn 10-50in, 40-200in, and a 5-75lb in my shop. All are dead on.

When bike manufacturers specify torque, the way overestimate for the very reason you are talking about. Product Liability. It's better to break the carbon than to break the rider. The bike can't sue them. You can.

Always follow torque specifications to the letter, though. If you don't have the tool, don't do the job.