Tempo text positioning for voice, piano & one extra instrument

[NeeraWM]

In a score for cello, voice, and piano, where would you put the tempo indications?
I've seen many examples and alternatives:

• only once above each system

• above cello and above piano

Following Gould I would need to put it over cello, voice, and piano, which I am not going to.
My preference would be: smaller above cello (which is also using a cue stave size) and once above piano.
What do you think?

[David Ward]

Once at the top and once above the piano, and I should have both iterations the same size.

[MichelRE]

I would have gone with only at the top staff, considering how small an ensemble it is.

Ravel has them over the top staff, over the voice AND over the piano in Chansons Madécasses. To me that's overkill. But then, I ain't no Ravel, either.

[NeeraWM]

Thank you both.
I'm trying to fit three systems per page (two leaves way too much whitespace) so three is definitely too much.
With the top staff (cello) being cue-size, I think just once on the top, but big and clear, should be enough.

[Anders Hedelin]

I'll go with Michel here. For a score of this size, tempo indications at the top only seems good enough to me. In every part there'd be tempo indications anyhow. No one would risk missing anything.

The space problem might possibly be resolved by further diminishing the size of the staves, and dragging them closer to each other.