My wife has the foot-swelling issue and wears compression socks that come to just below the knee during the day, except when she's riding. She tried it and it made her feet cramp, probably lack of circulation, lactate buildup, whatever. For sure they're good after a ride and when flying. There have been some studies done with compression garments for recovery, result was maybe 10% improvement. Some ultra-runners wear them, but I've never seen them on a cyclist other than my wife trying them a couple times.