Since I cribbed the original block generator design from a YouTube video, I really don't think you need my permission.
I've played with the design quite a bit. You want your source blocks at least 3 blocks above the ground. You want them with only one block space between them. Of course, your streams need to be contained, at least at the bottom, so they don't go everywhere. Four repeaters set to max delay is what it took for the device to produce a block every cycle. Less and the piston is going too fast for the cobblestone to reliably form.