Just a general question. What is the opinion on Overlining a rod?
+1Let the rod tell you what it wants...
If I were to find this problem, use the Common Cents method to measure the rod (not a perfect method, but fine, give me a better one) and then find a line that matches that measurement. So if your rod is called a 5 weight but actually just nudges over to 6 weight, then find a line that is also on the light side of a 6-weight grain weight. It's a lot of work that, frankly, is caused by fly rod manufacturers purposely misrepresenting their rods, but I don't see a way to force them to use a common method to measure their rods.