I think the biggest difference between splices is the amount of surface area. Different styles can be used depending on how much handle room you have or how much you're worried about strength. A shorter splice with more teeth will usually have more surface area than a longer splice with less teeth. I draw the splice on each billet and cut each individually. Splices which are not symmetrical like a z pattern can be cut with the billets clamped together. I think a helpful way would be to draw the splice on a piece of paper, cut it out, and tape it to the billets to use it as a template. This would ensure that each part fits together. Fine tuning work may need to be done so it's good to perform a dry fit to make sure there is as much surface contact as possible. Also very important is the glue you choose to use. I've done two splices. One with epoxy and the other with wood glue and both held up well. Ultimately it's the glue that's holding the splice together.