I have read all posts. What I found the most helpful is this:
The whole mark - from beginning to end - to me is 40'
So, when you pull the putter and stop halfway and release, your ball will travel up to 20' (depending on how fast the green is). If you are 40' away, go all the way to the end and then release the putter.
Similarly, if you are 10' away, go 1/4" of the bar.
Works every time.