No real wisdom here but I do remember the farm I get my milk off telling me they were going to hang the bull for 2 weeks but it ended up being 3 for some reason & the butcher had told them it was nearly too long. They hung it in the chiller too. All our beef here is grass raised so I could find out if you get desperate.
It depends on how old the beef is before hanging. We purchased an 8-9 month old grass-fed calf and they recommended hang time be only ten days because it was young. I think an older animal would require a longer hang time I had read about 21 days for an older animal. hth