I found one of those blocks yesterday by accident. I knew like 4.7 BTC fee in one block was a lot, but I didn't know how to find which transaction caused it (and I didn't want to go through it manually).

I notice something interesting: two transactions with 4 Bitcoin fee, within 29 seconds apart. And one of them is included 10 blocks later than the other.
In other words: does a higher fee really help for a faster transaction? What were those miners thinking skipping this one for so long?

I always believed a higher fee would give a higher priority, but apparently even 4 Bitcoin fee gives no guarantee to be included in the next few blocks!