When I start reading a (good) book, I tend to do a lot of highlighting, which I then aim to make more concise when I go back and re-read/grapple with the book. Perhaps this is a foolish process (and I'm open to any suggestions of better methods), but it is what I do.
As such, sometimes I have highlights that are back-to-back. Right now, they appear as one large highlight. So, it would be great if there were some sort of markers to demarcate them. My suggestion is to make use of the existing "Annotation White Dot" to signify the start and/or end of a highlight, and a colored dot to signify the start/end of an annotation. An example is in the attachment below, where it would otherwise be impossible to know whether it is 1, 2, or 8 separate highlights.
On second thought, it would be better with just a single trailing dot - as it is currently implemented for the white annotation dot.
An alternative would be to remove the margin/padding for the highlights so that there are no blank spaces between lines. But this is likely to be messy with indents and line endings, so I prefer the dots.