I average 24 disc a month and have hit 27 before.
Actually the netflix streaming library has decreased in size in the last few months. If its on STARS Play, or is a Sony Licensed disc it went away. They lost something like 30% of their streaming movies. Also if it is a new release you will not get it for streaming for a minimum of 30 days after release and in some instances it could be 90 days. They really have let their whole business model go to crap. If it were not for their huge disc library with almost every older movie I would like to see, I would drop them all together.
If you watch 10 or so movies a month and can get to Red Box's website quick enough to reserve a copy of the new release you want to see then that would work out great, but for me I am way to busy to take a trip to redbox, sort through the movie list, and then take it back the next day. I can update my netflix queue from my Android phone as long as I have some sort of data connection. This means I can add movies as I think about them and I can check to see whats up next or pull something from the bottom of the queue to the top.
At $15 for 3 DVDs at a time it's still worth it for me. I usually have a 1 day turn around on my dvds and as long as that stays true and they do not throttle me like they have other customers, then they will keep getting my $15/month. (Are you reading this Netflix?)