Same here. I have a sushi belt for asteroid chunks and ammo, whose primary function is being a buffer that can hold a bunch of items.

Then there is reprocessing hooked right into it, with a single decider per crusher to control it.

I’ve just built the first platform with railguns and was great improvement over rockets for big asteroids. I do find that going slower does mean less asteroids, which gives your guns more time to shoot them down and also more time to manufacture ammunition.

So even if there would be no correlation between speed and asteroid density, you don’t want to go too fast as that overwhelms turrets and manufacturing.