the problem is that even professional singers cant get it right all the time.
I recently sang[at gigs] willy of the winesbury,twice in three nights,the first time it was ok,the second time I really got in to it,in fact I have never sung it so well before or since,I thought afterwards how do i follow that.
one person in the audience realised and compilmented me on my singing of it[hello Helen Pitt].
the problem is we are not machines, that can always get it right 100 percent of the time,if we can get it right 50 percent of the time thats good, but its important to keep trying to get it right.