A one piece can be designed for a longer draw length on a short bow, because the risers on one piece bows are shorter than those on three piece bows. If you care about that, you can get a two piece bow with as long a draw length as the same length one piece bow. Some three piece bows are built with very short risers to do almost the same thing, but they can’t be built with as short a riser as a one or two piece. I prefer longer length bows anyway, so my favorite bows are three piece takedowns, because I find them easier to shoot accurately, for the reasons mentioned. I do have a one piece Schaffer longbow that I keep for longbow competitions that require a one piece longbow.