I found this quote some years ago and just subbed "collecting" for "singing/performance/&c" and carried on:

"Just before his death Albert Lloyd wrote about his approach to singing.

I very much doubt if I sing any of the songs exactly as I originally learnt them. Some I've altered deliberately because I felt some phrases of the tune, some passages of the text, to be not entirely adequate. Others - and this has happened far more often - have become altered involuntarily, sometimes almost out of recognition, in the course of buzzing round in my head for thirty years or so and being sung whenever the buzzing became too insistent. Some people believe it a blasphemy to alter a traditional song, and think one should sing it just as it was sung by the singer from whom it was learnt. Not being an impersonator, I do not feel that. One day a traditional performer sings a song, and the next week he may sing it differently. What you hear is the performance of the moment, merely. So with me: I don't always sing the songs the same. I like to improvise a bit. Of course, in making your changes, voluntarily or involuntarily, you need a proper sense of tradition and a just respect for it, or the song is violated; we hear such violations day by day."
[Albert Lancaster Lloyd]