I know the typical rule-of-thumb with sowing seeds is the smaller the seed, the more shallow the depth when planting it.

With stuff like lettuce, the seed is so small I just put it on the surface of the soil, and cover it with a thin layer of soil.

I'm wondering if I should do the same thing with other small seeds? Basically what I mean is just putting them on the surface of the soil and covering them with some soil, not even making an indentation or shallow hole in the soil.

The ones I'm referring to are the vegetable seeds that are very small-carrots, cabbage, kohlrabi, turnip, mustard greens, pak choi, etc.