When considering a new rod, always “fill in gaps” or get a length you don’t already have. (You cannot have too many rods!)
I grew up fishing 6 to 7 foot cane and glass rods for # 5 and 6 lines because that is what we had and they worked ! I have learned over the years that you can do things with a short rod that you cannot do with a longer one, and one feat is to be more ACCURATE !The tip is closer to the eye.
You can use a short rod in larger water but it is almost impossible to side-cast a rod longer than 8 feet up under the banks and limbs of some of our rhododendron choked headwater streams. After 51 years of fishing tight streams I am still learning………….. BUT, one thing I have learned is if considering two different lengths, go shorter. If considering two different line weights, go heavier. When fishing a tiny stream with a large bushy dry fly, weighted nymph, large streamer, etc., possibly in high water or wind, the heavier line will carry the payload better and the shorter rod will get under the limbs and rhododendrons with accuracy. Some will say that heavier lines are not “delicate.” With proper timing and motions, one can lay an 8 weight line on the water with barely a ripple.
Too many magazine articles have tried to convince us that # 1 and 2 weights are the stuff……………. bullsugar ! It is nothing but a marketing ploy to move new products. Try fishing tandem weighted nymphs or dry and dropper in tight pockets with a stiff wind or high water with one of those toys. You would laugh if I told you how many fly rods I have, but I do not own nor want anything below a # 3 weight and # 4 to # 6 is much more capable where extreme tight-looped accuracy is needed for our smaller streams.
I built rods for 22 years and still have some of the short 6 1/2 and 7 foot rods for # 5 lines. Additionally, I have a number of 6’ 2” to 7 foot bamboo rods marked for 5 and 6 weight lines that are very fast and highly accurate in our high elevation small stream gorges. With these shorties and that adequate weight line, I have regularly done a side cast with a bushy dry fly that literally “richochets” off the water at a calculated point and will bounce the fly up and under low overhanging limbs into those dark shaded side runs that spell “nice fish.” Short rods for heavier lines can do this. Short rods for heavier lines can literally be made to “point and shoot.” The one weight toys cannot.
Now, what is best all around for the smaller NC streams? I would pick a 6 1/2 to 7 foot for a # 4, simply because almost no company makes a more practical # 5 in those lengths anymore. If you truly want a rod to do it all, a 7 1/2 foot # 5 would be absolute maximum length and a great all around line weight.