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It can be. Depends on what your goals are. Usually a need for an extra ground wire is an indication that something is amiss, but it's also a quick and easy fix for a number of problems (if you don't feel like gutting your harness).
It is on some older bikes. On the GL1000 the condenser grounds by its mount and is easy to rust and lose a good ground so a wire to a better spot on the frame makes the ground never an issue anymore. But then the better fix is a Dyna which eliminates the condenser all together. I put extra grounds when I rewired my GL too so I had shorter runs of wire for stuff and an easier time finding a ground that may have gone bad etc.
I am a great believer in good earths and earthing. When you route the earth via the frame, there can be all sorts of paint, loctite, anti-seize, grease that gets in the way of metal to metal contacts and builds up resistance. As well as the main frame earth, I always take an earth up to the instrument cluster so I have a guaranteed good earth up there. I sometimes do it at the rear too. Tracking down earth problems can be the devils own job, so I prefer to over-engineer by a couple of wires or so.