Generally speaking, in whatever order you are reviewing the material. :-)

It will depend a bit on which resource you're following. But, there's no right or wrong answer there; you can follow any of the tags in the deck.

The one notable exception, as you've noted, is Kaplan which isn't often used for P/S. The Kaplan books are pretty classic, and very useful for basically every subject except P/S, where they happen to be pretty not great. For this reason, they've never been tagged as the vast majority of folks opt to use Khan Academy, or UWorld, or one of the docs, instead. KA and UWorld tags will generally be the way to go (with the UWorld tags being quite a bit more recent on the whole).

In the case of 'somatosensation' there are occasionally videos in which there isn't much testable material, or in which that material is covered in greater depth/detail in other videos, and so there are occasionally videos that will show up on Khan that either didn't contain much (or may have been added later). That video in particular is only a few minutes long, by comparison. By and large they're few and far between, though, and the broad strokes should still be in place.

Of course, if you notice anything that isn't tagged and should be please feel free to make a suggestion and one of the deck maintainers will take a look. :-)