Want a good way to find out how far you hit each iron? Try this.
Play a round of sprinkler head golf by yourself. Nine holes will do.
Play the first hole like you normally would. After that, hit your tee shot, pick up the ball and use the sprinkler heads or cement markers embedded in the fairway to stand at what you think your 9-iron distance (say) is. Then walk straight to the edge of the fairway and hit two shots.
You hit your shots from there so you don’t mark up the center of the fairway with your divots.
To know how much distance you have walked off from marker or sprinkler head, you need to know the exact length of your step using your typical stride.
Yes, I know, going to the edge of the fairway adds distance, but not much. With a fairway that is 40 yards wide, hitting from the edge of the fairway at 150 yard adds just over one yard (1.3275) to that distance.
In the notebook you brought, write down the distance club, and result–short or long by X yards, or just right.
It doesn’t matter if you hit the green or not. You can tell even when you miss if that was the right club or not and if not, by how much.
So you don’t slow things down, skip putting and move on to the next tee.
On the next hole, do this with your 7-iron, the 5-iron after that.
On par 5s, measure both the second shot where the ball ends up, not to where it lands, which you probably couldn’t determine accurately anyway.
After nine holes, you should have enough information to be getting a good idea how far you hit those two clubs. You can use the pattern they create to fill in the distance for the 8 and 6. Longer clubs you can measure on a long par 3, but don’t use a tee.
You might want to do it all over one more time to be sure.
Why would you do this on the course when you could get the same information from a launch monitor at a driving range?
The reason is to determine your distances under playing conditions, which are different than range conditions. There are very likely differences in the distance you will get from each, and the course is where you need to get the distances right.