You don't have to grind/sand the seed coating in order to germinate the seeds.
The stratification period is usually long enough to break down the exterior seed coat or germination inhibiting chemicals.
The reason I sanded a couple of mine was to test a method of skipping the process of stratification and/or scarification. This idea stemmed from a similar process needed in order to get Adansonia Digitata seeds to germinate. As I have had some presumed success with Carpinus turczaninovii, I decided to trial it with some Celtis.
In the case of A. Digitata, the fruits need to be consumed by an elephant and past through their digestive tract. Their gut biome breaks down the seed coating enough to allow water to penetrate through the radical and weakens it enough that the expanding cotyledons are able to burst open the seed coat. As someone who lives far outside if their natural environment, the only way to break down the seed coating was to use mechanical means. The down side to that being that the seed coat isn't weakened. So when the cotyledens expand, you usually have to remove the seed remnant after expansion.
