You may have room/space tags that overlap many other elements in the view. This is because by default, Revit places these tags at the location points of rooms or spaces, without considering other existing objects in the view.
Just run Tagitize instead. It will intelligently consider all visible elements in the view to give you the best tagging result.
If you think a tag can be placed better, just select it and click Next to tell Tagitize to try the next possible tag position.