Worse, if this is something that's designed to showcase one's technical skills to potential employers, I don't imagine there's a way for the system to distinguish between "took a long time solving challenges because just not smart enough" vs. "took a long time solving challenges because have a day job and a life outside of work/tech".
Since this is designed, essentially, to showcase how smart someone is to potential employers, assuming solving time is a factor, it's almost better not to compete until you know you'll definitely have lots of time to devote to it, because otherwise there is the risk of taking too long and looking not-good.
I'll add it to the long list of "things I really, really wish I had time for" - or I'll assign it to clone #1023 once that becomes viable :-/