
Mark revised
will indeed apply the current revision color to a selection. (That’s actually what the function’s name says it’ll do.)
Looks like you are applying the revision color, then try to have passages revert to black font (or default color font) as you revise.
If that is the case, you are using the feature the wrong way around.
Mark Revised
and Remove Current Revision Color
are the same menu item, switching to one or the other, depending on the cursor/selection being on text of a revision color or not.
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The feature is not intended to mark “revised passages” (as in : “This part I’ve read already.”), it is rather intended to mark where edits were made.
If you want to mark the text as revised as you go (“This part I’ve revised already”), simply change the font color of the chunk/paragraph to tin/gray as you work your way down through your text.

This way you’ll know where you are at in your revision of a document, and the edits will stand out by their specific revision color (blue, red, green). → Revision colors supersede font color.
Once you are through with your revision of a document, revert its text back to the default (or black) color. (Select all, color picker.) The revisions (edits) will remain of the revision color, giving you a clear picture of where (exactly, precisely) you made changes.
You can keep track of the revision process on a project scale by updating your documents’ status accordingly, at the bottom of the inspector. (That’s the selector right next to the labels’.)

So say you mark revised passages (not edits ; passages you’ve read through) of a document with the tin font color, you can set the font color back to normal without a problem once you are done with that document, without loosing track of your overall progress, if you mark the document as “revised” in its status. (You can create as many custom status tags as you want.)
“Revision 1”
“Revision 2”
Or even “Third draft - Revision 1”.
→ “Last Final draft - revision 3697” 
Anything that accommodates your own personal approach/method.
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In short : When used properly, you basically only have to turn the revision mode on, and edit away.