It's plain useless.
It may be, but I would like to see what are the chances that a guy with ~160Th/s finds 3 blocks in 1 day
http://bitsolo.net/pool-stats/No matter how lucky a guy can be its still consider gamble unless you have 1 PH... Pool is the way!!!
4 blocks in a day
I don't think you need to have enough mining capacity to expect to mine 4 blocks a day to be able to viably solo mine. I would argue that the figure would be closer to between .75 and 1.25 blocks per day (expected value). Once you get closer to the lower end of this range, you will likely be much better off mining on a pool because your variance can potentially hurt your return a lot.