Drawings are good if they help us understand what we actually notice. Otherwise they are useless. My chemistry teacher said years ago, "if a model fails to explain the phenomena we observe, we discard the model and make a new one.
So here is Mike reporting good results from stropping with green stuff on leather. And here is Winton with drawings to show Mike that what he noticed did not really happen. Ridiculous.
I have used a clean leather strop for five decades. We strop because it improves performance. We strop on both sides because we can notice the difference. I think the ruler trick would be helpful if you were to have a class of beginners and wanted to get them working right away. Or if you are getting a new plane iron every month and are tired of flattening backs. If you can use the same iron for years at a time, the ruler trick is unnecessary.