Sharpening is
entirely taste-based (subjective)*. It's also influenced by equipment, technique, subject matter, and intended output. The appropriate amount of sharpening appropriate for someone shooting hand held with an
IMAX 130/2 at f/2 is different than the sharpening appropriate for someone shooting on a tripod with a
Schneider 45LS Blue Ring at f/7.
The factory default is the "taste" of a small core group at P1 paying some attention to user feedback and to continuity. If the factory default is other than you prefer, then simply save a lower default.
Personally I find the factory default radius "just about right" but the threshold and amount higher than I prefer.
This applies to nearly any of the settings in a raw file. For example the definition of "0" contrast in C1 (or LR, or aperture) is entirely subjective. Some will prefer to start at a "+5" while others will prefer to change the base characteristics to Linear.
The important thing is that you can change the default so that, without any per-image action, your images all come in with your preferred starting point. Along with UI customization, this takes up an hour or so of our
Capture One Masters Program classes. It's really important to not give undue weight to the defaults established by some Danes; they are smart and well intentioned people but they can't fine tune the factory default (settings or UI) to
your individual and specific needs, wants, and tastes – only you can do that.
*Assuming that we're talking about creative image making rather than technically-oriented imaging like art reproduction, machine vision, scientific measurement etc.