It varies depending on aircraft type but no more than four rows, so 16 passengers in total.
On 767s, A321Ts (in J) and 777s on domestic flights where cabins are quite a bit bigger than 16 seats I normally find you have a tray of orange juice and water are brought around.
I fly AA FC a fair amount and I'd say I have about a 95% hit rate in terms of getting a full offering of PDBs.