It all changes if it's used in conjunction with the word 'session'. A singer's session and a musician's session are quite different things. In a singer's session it's one at a time, you take your turn and then wait for every one else to have a go before you sing again, except for joining in on choruses of course.

A mixed session accommodates both singing and tunes.

In a musician, or 'tunes' session it's tunes only. Someone starts a set of tunes and if you know it you join in. If you know lots of tunes you can play all night. An occasional song in a tunes session is OK but too many attempts a singing can result in hostility. People go to tunes sessions to play tunes, not to listen to singers.