I've mined on this pool for 4 weeks or more starting around the end of September. Despite the PPLNS stats which shows arround 96% I think the real stats are around 75%, or maximum 80%.
In the pool news posted on September 29 it states that the pool will take around 3 hours and 20 minutes to solve a block on AVERAGE. This means a little more than 7 blocks per day, which happens only once or twice a week. On September 29 there was an entirely day with only one block solved, so, bye bye BTC Guild.
Missing you already. Mind you take the time to read up about luck and probability before complaining that the next pool you try also doesn't meet your expectations.
Eight days ago I withdrew my earned balances from both BTCguild and Slush. Starting from zero, and with equal effort, the earnings on the two pools are very similar. Sometimes one gets its nose in front, and sometimes the other. So I don't have any issues with the day-to-day or even the week-to-week variance in luck.
Edit: I took the time to work out some figures. In the four weeks 1-28 October, there were eight days when 8 or more blocks were found, so yes - two a week; the highest was 11 blocks on three occasions. The good days tend to offset the bad days; over the 28 days there were 189 valid blocks, so the daily average was 6.75. It would have been slightly higher but for an orphan on the 27th. So perhaps a little below expectation, but not by much: by my calculation it is 93.75% over the four weeks, well within what I would consider acceptable tolerance.
And your "napkin math" calculations are very close to the reported luck for the last month. Who'd have thought that actual math trumps people's gut feelings?