If the blade was longer, you wouldn't need to reposition the work so often. You really want to make it as efficient an alternative as you can, and that means each split of the work piece should take one stroke. You could move the pivot point a few inches out, and make the blade deeper, which would also save you energy on the stroke.

And if you really wanted to get ambitious, you could make the cutting blade from heat-treatable steel, and that would also increase cutting efficiency.

But I like the concept. I may make one and test my theories, put my welder where my mouth is.

TheElderBrother