I agree it is not against the rules as written. We do have a ‘guideline’ of 40 seconds to play a shot. The people who use the line tend to violate this guideline, especially Pros.
The green is the only place we don’t have to play it as it lies.
I tried the line a long time ago one half season. It was slower and didn’t seem to help. Then I read a Stan Utley’s The Art of Putting in which he stated that many good putters don’t even have there dominant eye directly over the ball. I did the test in his book and my dominant eye was inside and behind the ball by about and inch. So using the line, which requires my dominant eye above the ball, would require me to change my stance. So I got fitted.
The result of the fitting was my aim was pretty good (1/2 cup left). A few adjustments to loft, lie and length and I was dead center. Now I put the ball down with no markings at all to distract me. I use AimPoint to read, which is fast and take no practice swings, which is fast. If my ball is clean and not in the way of another player, I don’t even move the ball at all.
It makes me crazy when I see Bryson D take two minutes to line up a putt with the line and his putter shaft and remark and move 5 times. I get overjoyed when he misses.
Wow, that's interesting. I looked at this list and it's different.
LPGA Tour Money List Leaders - ESPN
Find out which LPGA Tour golfers are the biggest bankrollers at the Money List Leaderboard on ESPN.com.
But again, it doesn't matter. I enjoy watching the LPGA. No law says you have to.