Alex Glasgow wrote a song called, I think, Sammy Bell:

A little tale I'll tell of a chap called Sammy Bell
Who lived down our street
He laboured night and day In his way
Making sausages for you to eat
But unlike you and me he was always full of glee
As he worked away
something something you could hear Sam's song

Oh, I love my work and I love my wages
Love my Boss, and he loves me to
Oh my lovely line of sauages
I'll surely die for the love of you

A strike is called by the workers, but Sam refuses to join in - in fact he goes in and tries to run the production line himself. The factory noise ..

... rose to a high-pitched groan
On a sausage skin Sam slipped
By the mincer he was gripped
And it didn't take long ...
before the sauages were coming out the other end
and they were singing Sam's song!

Oh, I love my work and I love my wages
Love my Boss, and he loves me to
Oh my lovely line of sauages
I'll surely die for the love of you

Back to the thread. I can imagine how Tin Pan Alley would be run now ("You've only produced three outputs this week and one of them did not mean our quality standard for a 'song' - if this doesn't improve we'll have to let you go"). Obviously, they didn't just leave the songwriters in a room for months and hope something came out. So how did they run it?