I make the assignments each day and like the post above I feel that if you're on call to do everything you need to know how to do it all. I do try to rotate things around to keep it fair and it doesn't take long to figure out each person's favorites. I also try to mix it up with our more "difficult" surgeons and tough cases as to not burnout staff (some weeks this is a bit difficult).
I also try to give the surgeon's their favorite nurses and/or techs if they've been tough for others to work with in order to get them back on track as well so that we give the patient the best care we can and keeping staff and docs happy while doing so