100 nm without a torque wrench

[VNA]

A torque wrench is only as good as the last time it was calibrated which should be Annually.

All depends on what you are doing.
I doubt I'll ever calibrate mine.  It's not gonna get that much use.  It will be religiously wound back to zero when it is not in use.  In short buy a good one, treat it with respect, look after it and it'll last you a life time. 

On the other hand at my work annual calibrations are not acceptable.  We don't use wrenches with scale markings, only a range mark.  Each wrench is set before and after use on a torque wrench analyser.  It's the torque wrench analysers that get calibrated every year.