At least half a sleeve when eaten alone - somewhat less when eaten with cheese. In another life I used to eat far more, but am reformed. I once ate a whole sleeve while bombing pack rats.
I try to not do it, but 1/2 a sleeve is normal. I prefer Townhouse Crackers to the Ritz, but same issue there. I use a whole sleeve of Ritz/Townhouse when I make Cracker Chicken for supper though.
I can't buy Ritz because I have a habit of just sitting and eating the whole sleeve! I just really love Ritz crackers. Especially a good summer sausage.