NOTATIO

With an orchestral score it's normal to have a tempo marking at the top, then at the brass, then above the strings.

With a piano concerto, there's room for a tempo marking above both soloist AND strings.

But what about with a woodwind or string soloist? It seems visually redundant to repeat a tempo marking immediately two staves in a row.

I'm looking for guidance here.

Usually, the tempo in a full orchestral score goes on the top (Woodwinds) and on the Strings.
Having a soloist doesn't change that, the tempo is not found on the soloist.
So, yes, it is visually redundant.

thank-you.
I'll make some changes.