Thread: Why lapping film rules

but I just bought .5 and .1 from Lee Valley which is quite a bit more expensive

That's the reason why it stops at 1µm. The 0.5µm und 0.1µm are a little more expensive.
It sucks that they did not tell you what grits you would get

But since the 0.5 and 0.1 will be used only for a couple of very light strokes for the finish, they will last you a long time.
Btw. I just finished over 20 razors in a row on the Al2O3 lapping film without a replacement.
I used a 5µm for setting the bevel and jumepd directly to 1µm for the finish. Perfect!
And even after 20+ razors, there is no sign of extensive wear. It seems they still got a lot of life left in them.

Here is a recommendation for you. Try using the lapping film with just a hint of dish soap in the water.
It prevents lutos effect (especially a on the 1µm film) and it helps to wash out steel swarf from between the abrasive particles of the film.
I think this helps make them last longer