Are all those checks from the same bank account? As I understand, G mailed out the checks from several regional offices.
I'm telling you right now that if I had 70 sites and over 20 million page views I'd have a lot more than $600 a day. Granted, that blog site probably has some fairly crappy keywords they're using, as most blogs do. I'd guess 90% of them payout around 3-10 cents a click. They've got the traffic, they just need to get more blogs that are niche and payout a ton more. $600 a day is nothing.
Yeah, I have to say, $600/day for a page that gets over 20 mil page views doesn't seem like all that much.
Well $100 per day for 200,000 page views seems in line with what I would .... expect for a low paying keyword.
I guess it's all relative to what your target market is. When kids are blogging on Britney spears, the keywords are probably worth junk. The traffic is high, but the monetization for the keyword is low.
I personally think a better strategy with AS is to optimize for higher paying keywords with less pages...well SE optimized.