There is a ~3% chance of 0 blocks vs 3.6 blocks expected in 6 hours is due to luck.
There is a ~1% chance of 0 blocks vs 4.8 blocks expected in 8 hours is due to luck.
There is a ~0.2% chance of 0 blocks vs 6.0 blocks expected in 10 hours is due to luck.

Assumes AM is operating at 10% of network hashrate (well technically 10% of the hashrate required to sustain the current difficulty), if AM is lower then the chances would be higher.