In a low country boil, I cook the shrimp separately to avoid overcooking. I also immediately chill to prevent "overcooking" which makes it the devil to remove the shells. It only takes two minutes to cook shrimp in boiling water. If the shrimp is not to be immediately eaten, after cooking and fast chilling in a bucket of ice water, I keep it chilled in an ice cooler with frozen plastic water bottles rather than ice which would melt and make the shrimp soggy. Why the trouble? Years ago at the Beaufort (SC) Water Festival, the low country shrimp was kept warm for several hours before serving to the thousands of attendees. Over a hundred folks came down with diarrhea and stomach aches after eating the shrimp.