When you look around there are a lot of flounder spots to fish, you don't have to go where the crowd is. Focus on those classic flounder ambush spots, bulkheads, pilings, rip rap, corners/points, cuts, passes and out on shallow flats when they are really feeding.
Marsh drains are killer as is any funnel down of the water flow. It seems they can be aggravated into biting when not actively feeding, and when they actively feed they are ferocious. Fish extra tight to structure when the water is not moving or they don't seem to be active.
When fishing long stretches of structure like bulkheads and rip rap really fish those spots that are just a little different, the rocks are bigger, or smaller, the wall or bulkhead has a slight dip, any break in the line of structure.
But cover it all as the bottom holds changes in structure you don't see.
It seems flounder will stack on top of each other in a tiny area like a depression on the bottom.
I caught 16 flounder in a row once fishing Fish Pass at PINS as it drained into the gulf, well above the surf the pass was a trickle and made a pond before spreading out to wash into the gulf. I cast the same cast covering the few feet of the middle of the pool. Taught me to keep a plugging a spot when I catch one.
When I was primarily a saltwater fisherman I used to catch flounder year round, not as many after most go out to spawn, but there are still a lot around.