Ken Matson is a 40+ year veteran of bands, starting in the late 70s as a teen. He also ran a commercial recording studio for 10 years. Currently, when not at his day job as a software engineer, he’s moderating the Keyboard Players in Cover Bands group on Facebook (~ 14000 members) and playing in his weekend warrior band, Random Access.
For me two keyboards is ideal (weighted 88 on bottom and 61 synth action on top).
I feel absolutely no desire for more. And, I like the keyboard options (synth or weighted) and greater keyboard real estate (so I can normally play everything where expected on the keyboard) than one keyboard may allow.