By default I play irons with full backspin and usually less than full power. If I have 122 to the hole, a 120 club will be 2-5 yds short, depending on how well I hit it. So I take a 135 club and back off the power a little. I found that the lines delineated percentages. So the line in the middle was 50% of the clubs rated distance. Makes sense.
I found the first line was roughly 10%. So a 180 club , when that first line was used, would result in the ball traveling about 162 yda. (180 - 18). All of this of course has to take into account elevation and wind, but that is what makes it challenging. If I had a 143 yd shot with a 150 yd club, I would need the to hold off 7ds. 10% is 15yds. So 5% is 7 or 8 yds. So I would take the power halfway between full power and the first line. Simple. As I got better at this, my distances were within 1 or 2 yards of the desired distance. ie. 143 yds shot was consistently 141 to 145 yds. And often 143. (left or right was something else entirely).
So we get to the point of this thread. In the last week or so, this has gone right out the window. Balls hit this way were coming up drastically short. Like 10 or 15 yds short. I thought maybe I was missing something. But I wasn't. Where in the past my short and medium irons were spot on, now they were coming up short. I had to go back and learn new power levels. I'm getting the hang of it, but the 10% line was very handy, as clubs go up in 15 yds increments and that is roughly 10% of of medium to short irons.
Has anyone else noticed this?