You dont apply for it until you want to come back for that extra year. i.e. if someone got injured in their 4th year after taking a redshirt, they wouldnt apply for a 6th year until after year 5.

I would *assume* thats how compliance will handle these situations to keep everyone from being confused. Everyone will stay on their Freshman, Soph, Junior, Senior track and if they choose to cpme back for the extra year then theyll be called either a 5th year or 6th year senior