It depends. If it is taking set then yes, use more wood. If not, then you are fine like that. If you want a full compass bow adjust the length and width to justify using the extra wood in the middle. But if you have plenty of wood, working the center will just rob cast.
"ELB" is such a ambiquious term/design. The 12th thru 15th century war bows were totally different than the Victorian era (and even thru to the early 20th century) "lawn" bows, although other than tiller shape, draw weight and lenght they were virtually identical and frequently referred to without distinction.
I personally favor the full compass look, allowing only modest movement directly under the bow hand. But this usually doesn't require the typical elb lenght, rather more like typical woodland bow, closer to 60" ntn rather than 70" or more.
