Guitars look better if everything on them looks like one person did the work, rather than a committee having been in charge. There is a tendency among some luthiers to load their instruments down with as much “gingerbread” as possible. While this is not exactly a crime, problems arise when some of the decorations work against others, and certainly when there’s much more there than needs to be. I think one should eschew visual aesthetic pleonasm. Or even verbal pleonasm. As it were.
Any individual inlay can be beautiful, but one can distract from another one, or they can clash. It is better if there is an inlay or highlight that “goes with” another one, or carries an echo of it. It doesn’t really have to be a separate element either; it can be an elaboration or enhancement of something that is already there.
Here are some examples of echoes and accents, from my own work.