While working with another woodworker on planing he noticed me tilting the square while checking the work. When asked it really didn't come to mind why I was doing this. Today while working in the shop I noticed when doing this the way my bench is set up with the lights it puts a shadow on the viewing side of the work highlighting the area between the work surface and the try square blade.
How many of these unthought of techniques are habits which we have forgotten yet still use?
I guess if we have forgotten them, we will never know the answer.
jtk