The length of a song is (or should be) immaterial if it is well sung.
Of course a badly sung 20v ballad can cause you to age visibly during its 'execution' (an apt term in some cases). But on the other hand a poor (or even a good) three-verse song badly sung can sound like an Homeric epic performed by a 'fit-up'.
The late Frank Harte could perform any song with skill and panache, but he had an awful tendency to forget words. On one occasion during the singers concert at the Willie Clancy Summer School he stepped on stage to do his spot. I heard the MC (Tom Munnelly) request in a stage whisper that he should sing a short one as they were pushed for time.
Much to the amusement of Tom and the audience, Frank (out of pure divilment) launched into a long song, dried up half way through, started another long song and dried up on that one half way through.
It was the highlight of the concert and every singer got their turn.
Jim Carroll
PS I too favour harmonisation on occasion, but it requires a level of sensitivity on the part of the audience - not always forthcoming.