Most lost overboard are permanently lost due to loss of visual contact. In any type of seaway it is scary how far you CAN'T see. To illustrate, have a crew member toss a floating object overboard, wait 15 seconds, and then call out MOB. In any significant seaway you'll never see the object. Kind of makes one reconsider that stylish black foul weather gear. International orange does seem to show up the best. Tossing other floating items over-board, immediately, does have merit although drift characteristics will vary widely. The single most important factor is CONTINUOUS visual contact with the MOB. If crewing allows, one person should be delegated this duty, without relief, and with absolutely no other duties until such time as multiple crew members have visual sight of MOB close aboard.
The tragic irony to such situations is that the MOB can see the vessel quite well, but all the yelling and waving in the world does not make them any more visible.