I tried it twice, and only made it once. The first time, I chose a bad time of year--it was right around the December holidays--that was not a smart move on my part.
The next time, I succeeded, but just by the skin of my teeth. I think I came in with hub 30 on day 29. A day to spare! Whew!
It was an interesting experience, but I don't think I'd do it again. It became stressful, and a bit too much like writing assignments from back in my school days, which is to say, it took a lot of the joy out of writing, because of the "have to do it" pressure.
Of course, there were no teachers breathing down my neck threatening my grades if I failed, but I was under my own pressure, as this time I had to prove to myself I could complete the challenge.
What it did do was give a major boost to my traffic and readership. Next time, if there is one, I believe I'll write out the hubs at my leisure, an extra one here and there, and have a stockpile ready to go.
(I was informed by an authoritative source, that, that is NOT considered "cheating.")