I'm not talking about holding it taut, but width wise I don' think my strop is flat. In some spots the edges seem to raise a little higher than the center. Since I'm not putting any pressure on the razor, the center of the blade does not seem to be getting stropped.

In HHT tests, this seems to be the case. The heel and toe ends grab the hair nicely, or will cut them, but the center of the blade doesn't grab much at all. I can also see a difference in the reflection of light on the edges compared to the center.

Is this why people often draw the blade diagonally across the strop, and not straight down it? My strop is wide enough to accommodate the whole of my blade, so I have simply been running the razor straight down the strop.

I'm realizing how much easier this would be if my father had known all this and taught me in person when I was a teen. It is difficult to get without someone with you, even with the wealth of information and videos available.