I made a discovery today as 'big' as a 'small' adjustment of a violin's soundpost. Every string instrument has a unique string tension that exaggerates overtones and resonance even if it is not tuned traditionally. A collection of acoustic ukes made of different wood tops with silver strings all tuned to thier best resonance and playability, - cured all the deficits of each instrument-.

Playing with others is sometimes resolved with a capo, but for solo work its great. Deficits cured are: buzzing frets, unevenness of tone, poor respondsiveness, no ease of play and lack of sustain.
Ease of play is by far the most helpful. It helps playing all tunes.