These phrases have a different meanings and it’s important to highlight them
I think of "Yak-Shaving" as working on peripheral aspects of the project, to the detriment of the main path. Easy to justify, as they are "working on the project," but maybe not helping to significantly advance it.
I think of "Bikeshedding" as working on another aspect of the project (or a completely different project), because we want to (often, because it is more approachable or pleasant). This often becomes a problem, when the project is getting near shipping, as there's a ton of really boring stuff that needs to be done.
"Perfecting," on the other hand, can look like either of the above, but is, indeed, working on the main path, and advancing the project; just maybe not quickly.
Quality takes longer. Sometimes, significantly longer, for many reasons. That’s why something top-shelf, costs so much more than commodity, when it doesn’t seem to have much more, in the way of features.
Many orgs aren’t interested in spending that much extra time on it (which is their prerogative). The customer base tends to be smaller, and a lot more fickle. It’s really difficult to make a living, doing top-Quality work.
Source: I worked for many years, for a company known for top-shelf stuff. I’m quite familiar with Quality as an everyday feature.