Depends on what you mean by "area." I rarely make more than 10 casts from a single spot before I move down the bank. Sometimes that move might be only 5 steps, sometimes 50 ft.
If I'm targeting shoreline cover, I'm constantly moving to the next piece of cover. If I'm working a drop off that's only a few yards off the bank, I'll make a cast (maybe two), then move down the bank 5 feet and try again. If I'm working a spinnerbait, crank, or even t-rig further from the bank, I'll fan cast the area from one spot (8-10 casts), then move down the bank about the length of one cast and start again.
Think about when a guy in a boat moves down the bank pitching to stumps or combing a grassy flat. He's moving CONSTANTLY. You can move as fast as I do and still be way more thorough and methodical than a guy in a boat.