"How many 'takes' of a song have there been before the one selected as a 'keeper'? "
A collector records and keeps every - try checking some on-line collections
We tend to use the fullest and best quality ones for albums
This is yet another failed attempt to suggest that collectors filter what they collect through their own personal tastes
Not a very good point at all

I don't know what collections Ord (wonderful name for someone involved in folk song study) is referring to
The only collector to have ever done what he describes is Peter Kennedy in his themed multi-cassette series - he was castigated universally for having done so
It is not common practice   
I suggest you find out if that is what he is referring to
And another two Harkerisms bite the dust

"sorry didn't mean to stop the conversation!"
Far from it Al - you made an important point
I'd like to discuss it more when the dust settles
Jim