My best advice is to tiller the best you can, then use your weak limb as your top limb. I never cut a shelf until I get finished tillering. It is much easier to loosen a limb already weaker. Most of the time, i identify my weaker limb, while tillering and just keep the limb weaker and work it as such. I only tiller to 1/8" to 3/16"positive and no more. Ive heard of some going as much as 3/8". Ive always shot for 1/8-3/16". I shoot three under, so I do my final adjustments when setting my knock. Ive never had any problem with hand shock or finger pinch. Also, split finger shooters can adjust the knock with no problem as well. I actually shoot in new bows with split fingers. Its hard to hold an arrow on a naked string shooting three under.