Tone, in the singular, doesn't mean too much to me
We have access to a range of different tones and use them frequently in speech
Unfortunately many singers do not apply to that in their singing, which indicates to me that they are not engaging emotionally with their song
They 'tell' their songs in a monotone - if you did that with speech you would soon be labelled 'boring' - think E L WISTY or Alan Bennett - brilliant in their boredom, both of them
Even with a song a tone has shades - get them right by feeling the song and the song can work - get them wrong and they can become boring
It's even worse when you use the singer uses the same tone for every song - or all the other you're sharing the session with do - probably why long shanty sessions never work for me
Exploring your voice so you can fully use it is, I believe, the answer to accessing the entire repertoire
I don't believe "right" or "wrong" should come into any of this Dick - the singer decides that each time
Jim