I don’t have RAC cover, but several friends do, and their default estimate for arrival has been 4-5 hours on the 2 recent occasions I have heard about.
One friend has a chronic, painful ( not life threatening) condition, and had broken down at night on an unlit back road which had no footpath, and a 60mph speed limit.
She waited over 30 minutes on hold before being connected, and was told it would be at least 4-5 hours.
She had an issue with her battery and her lights were rapidly dimming, so was in a very dangerous situation.
Fortunately she was only about 10 miles from home so I went and collected her, with then intention of taking her back when the breakdown vehicle was on its way. They were due to phone when en route.
Eleven hours later we had daylight and she had still not had the call so with some help from neighbours we went back and towed her car to the local garage.
We did let the RAC know as we didn’t want them having a wasted call out which might have meant someone else waiting longer than necessary. They didn’t even seem surprised.