There is now overwhelming evidence that having a larger hand span is a big advantage for a pianist, assuming they wish to have access to any advanced repertoire of their choice.
The evidence comes from different fields, including piano-related pain and injury (epidemiological and clinical studies), principles of ergonomics and biomechanics, statistical information on pianists’ hand spans and what this means for playing piano repertoire, and from the experiences of many pianists who play on narrower keys that better suit their hands.
In addition, the gender imbalance among prize winners of international piano competitions and solo performing careers supports this evidence, given the significant difference in male and female hand spans.
Refer to https://paskpiano.org/evidence-of-the-need-for-narrower-keys/ for details.
