....and you "know" you're off 5 degrees HOW? For me, it's not open for debate. I based my recommendation on my opinion and personal experience. In other words, how I would do and have done it. So an argument here is pointless, although I certainly appreciate you breakin your cherry to point it out.
The 5° measurement is worst cast. I have no cherry to break and you're coming across pretty defensive. I'm just pointing out that you can eyeball it and have results that are 99.6% as accurate as a $$$ tool.
So yeah if you can't eyeball 5° (or better) then get a tool that will do it for you.
