DC, That sounds right for most longbows. If I'm making a double looped Flemish, I make the lower on a bit smaller, it doesn't need to be moved in the stringing process, and the tighter loop helps keep the string on the bow when its unbraced.
For many historically accurate Indian bows you would need to widen the loop because of the wider tips.
Short recurves with siyahs and string bridges are usually made with large loops. I have little actual experience with those designs, but I assume the larger loop functions better. Someone who knows better will chime in.