I've had to wait more than 10 minutes on several occasions at Socastee. Also if there are any boats within sight they will wait to let everyone go at the same time.
Socastee bridge has never been a good experience for me. The bridge tender will seldom acknowledge a radio call, and always would make us wait while going in circles.
The worst bridge ever, and I oughta know, was Sunset Beach. During the last few years of operation they could not open during some low tides. It could be 3 hours in some instances, and because only the smallest boats (and I do mean small) could go under, the openings resembled a traffic jam of all different sized boats, and rude behavior was often encountered. Once during high wind, it actually was stuck in the closed position for several hours. Not only could boat traffic not pass, but car traffic too. I was there in my Boston Whaler and along with two other boats, we actually helped push the bridge back into position so car traffic could get on and off the island. A loud cheer erupted when the bridge clunked back into place as vacationers had waited hours to get off the island.
I finally figured out the protocol at the old Sunset Beach pontoon bridge. SeaRays had the right of way.
Anyway, as long as we're talking bridge etiquette, when traffic going both ways always let the side with a following current go first. Also, let faster traffic go first --- they'll only need to pass you later and those of you who have slow boats know how much of a pain passing can be at times, especially with some of the more hard headed sailor friends!