There is a tremendous amount of repetiiton here. I messed up 4 ribs by removing the forward tabs on 8 ribs vice only 4, that had the aft end trimmed. I had to buy four more, which emphasised the old adage of "measure twice, cut once". I should have read the instructions a couple more times. After that expensive lesson, I now read each step again before I do it, after reading the entire section a couple times.