I believe the "Book" says somthing about utensils and cutting boards and other food surfaces should be cleaned and sanitized every four hours.
Of course, common sense should prevail here. You know that you should never use any equipment that was used in prep for food that is now cooked.
This goes for tongs, cutting boards, pans or plates used to carry the meat out in etc.
Also since summer is here and the "Flying Maggots" are out, I would change or wash tongs as often as you see fit.
Keeping a five gallon bucket of water with a very, very, small amount of bleach in your cooking area isn't a bad idea. You can place your tongs in that during the cook.
HIG suggests fifty parts per million as a "Sanitation" solution when using bleach. For home use I would probably use less.