Help me understand, pt 3

Thanks guys for answering so many questions. I fully intend to order a new bow... as soon as I am confident in my selection. I have asked lots of questions so that I might make an informed decision. ..........So, help me understand riser length. I have a very short draw. I tried changing it by different anchor points, but I was only fighting against my natural tendency. So, I have put that behind me. Fully invested in "my way". If I had a 15 inch riser with short limbs, would the draw be essentially the same with a 24 inch riser with the same short limbs? I'm thinking that the "draw" would act the same on both risers, that finger pinch would be less on the 24 and that speed would be different, the 24 being slower????? Have I assumed wrong? My point is trying to figure why it is assumed by many bowyers that 24 to 27 inch draw be a 56 inch bow. Is this because the short riser does have affect... or only because everyone intends to build a fast bow? My thoughts are that if draw length is not affected by riser length, only affected by limbs, then I may opt for a bigger bow than 56, going for more mass.