Speaking strictly for myself, I've found recurves seem smoother (easier) to draw with a short riser and longer limbs than with a longer riser and shorter limbs in the same length recurve.
This is why with my 66" recurves, the risers are 19" long and the limbs are 23.5" long.
I've shot 66" recurves with 21" risers and 22.5" length limbs and I can tell the difference between the two riser and limbs lengths.
BTW, I would "figuratively" speaking kill for an all wooden 68" recurve with a 19" riser and 24.5" limbs and where the shelf is cut 3/16" past center, but I haven't found any custom bowyer who makes this recurve configuration.