The usage of the keyboard and Registrations is going to be a little different for people that sing like our friends DonM, Donny, etc....

And for the few of us that are only instrumental music, we most likely are to use more sounds for the verses, chorus, verse, etc....since those are our "lead" voices....is also a way to maintain interesting the song,
it gives some dynamics to the song, among other ways like changing style variations, modulation of keys, etc.

This is a common thing to do as an organist....and I just translated it to the keyboard, only that now the keyboards allow us to sort of becoming sort of a musical genre "chameleon".....

If playing a Bing band song, you can assign a solo instrument to play the verse (Clarinet as an example), a woodwind or brass ensamble for chorus, a piano to get back to the Verse, or trombone, etc....