My only set that required true endurance was my 1975 Topps on the PSA registry. I love the set (it was the first full set I owned as a kid) and I thought it would be fun to tackle it, well, it proved to be more of a marathon than a sprint. 660 PSA 8's and up became a rather dull feat after a while.
I love the set and I enjoyed piecing it together, but there were times I had some serious doubts about whether I wanted to complete it. I finished it 4 years ago and I haven't attempted another registry set since. If I were, I would try to tackle the monster
