Say cut 1x5" metal. If cut 1", only the front few teeth cut it. So it takes less time for the teeth to go through the 1". Same for 5", it takes a lot of time to go through 5" at a same speed. The rest of the teeth just dangling there. In reality, maybe they all sink in a little, but the force is just not enough to push the whole row of 5". So maybe the front is pushed down a bit and the back. Saw cutting is somewhat similar to lathe cutting, a few thous here and there make a big difference. So if the saw blade don't bite down, it wouldn't cut much. For a wide piece, it's hard to force too much, and the teeth wouldn't bite down either. Like lathe, it starts out below the surface to cut. If we do a plunge cut, it works, just not so good, and that's an equivalent of 1 tooth. Plunge cut of 20 or 50 teeth must be very hard, and that's why it's much slower. It just doesn't cut deep enough. I think if people want to experiment, they can try both and compare the shavings. I don't think they're the same.