I too, can't believe all the rules for growing rhubarb. Mine has been in the same spot for 40+ years, I pull the stalks when they are tall enough to use. I pull all of them. I usually harvest it 2-3 times a season. Depends upon weather, rain etc. The only rule I follow is that you can pick it when ever you want but never in the months that has an "R" it. Don't know why, but by Sept. I'm full of rhubarb. And I harvest every stalk when I pick it. I never leave a stalk.