I agree with Barb. There aren't too many "Cal Ripken's" out there who never miss a day of work. Be it a sick day(s), vacation, flooded basement, broken-down car, "hit by a bus", or whatever, there is a VERY high likelihood that your employee will not be there every workday of the year. If someone else can handle the job just as well as a backup via training, no problem (no written procedure needed), but if not, better have it written down.