I just received the 2015 catalog from the Hook & Hackle Company. On Page 4 is their guide spacing chart, showing spacing for 11' 6", 12' 6", 13' and 14' rods (ten guides each).
With the rods I've built, I use existing charts as a starting point. As long as you use a reasonable number of guides (when in doubt, add one or two), increasing the spacing as you go from tip to butt, and adjusting to work around the joints, they all work properly and look normal. Don't sweat a quarter-inch.