why do you care what is happening at the other table? either you're happy with your meal & service and will tip accordingly or you're not and shouldn't. what is happening next to you is irrelevant, but be sure to tell the server before ordering how you feel about tipping.

I like to use minimum wage as a gauge to compare my tip against... Never been good at social comparisons... I figure if I see the waiter taking care of 4+ tables, I reckon this hours been good for them and I can get away with a bunch of $1s, but what if the next few hours is super slow and only one or two people show up after I'm gone? Maybe I need to lay down those ones and a five. What if today's a holiday and the 5 tables I see right now IS the breakfast/lunch/dinner rush? Gotta lay out a $10 too. If I'm the only customer when I arrive AND when I leave, definitely, it's gotta be $20 or maybe 2. If it's that confusing, just take a week off and get a job as a waiter... You'll learn real quick what YOUR preference in tips would be. You'll do the right thing. I'm sure of it.