I already entered the Nicholl. I've previously quarterfinaled there 4 times with different scripts. (quarterfinal = top 5 percent). From that I got a handful of industry people requesting each script that had quartered. If you get high enough, scripts will sell and get made.
The Blacklist is more of a real-time event. There aren't specific entry times. It runs continuously, in real time, so scripts are constantly being uploaded or removed by their writers...
I currently have a script on the Blacklist. (A retelling) titled, The Velveteen Rabbit Redux.
It scored high enough to be on the "Top Uploaded Scripts" list, which sort of highlights the higher scoring scripts. You don't have to be high scoring for someone to download your script, but there are a ton of scripts there, so the highlighting helps. Otherwise its a sea of scripts people are slogging through. So far I've only gotten 3 industry pro downloads for my current script. So, we'll see....
...(if the script had scored even higher I would've been included in an email blast that alerted EVERY professional on the site -- producers, agents, managers -- to the script... I had previous script do that, and got 16 or so downloads, but nothing has come of it so far.)...
It's one of those, be-as-perfect-as-humanly-possible-and-then-have-someone-nitpick-every-thing-you-do-to-death. So, it's a lot like writing kid lit in that aspect.

:

I do want to make sure everyone knows -- this isn't a lottery. It costs money to host and get a review. The reviews don't sugar-coat anything. This isn't a hand-holding experience. They hand out 1's and 2's in categories all the time. Most scripts will get zero traction. Even a high-scoring scripts might not attract attention. You are "competing" against pros.
http://blcklst.com/about/