There are two basic classes of fasteners. The first is applications where the axial load applied is critical, as in bearing caps and head bolts. In these applications, the fastener acts as an extremely stiff spring that loads the two faces together with a force greater than the dynamic loading exerted by the engine when in operation. These are torque and tension critical, and the fastener actually stretches as it's tightened down. I always torque these.
The second class are those that hold parts on that are not loaded significantly in operation such as side and cam covers, and the main function is to compress a gasket to prevent leaks. For the most part, I don't use a torque wrench. Through experience and a sense of feel, I can tighten these adequately by hand. The 6mm fasteners seem to be the ones that always get reported as stripped or twisted off in these forums when a torque wrench is used, and I'd suggest not using one on them just for this reason. Almost all of them are non-critical, and would result in a minor oil leak at worst if not tightened enough. Just because a torque is listed in the manual, it doesn't necessarily mean one has to trot the torque wrench out. It's only a guide.
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