Incidently the RFU part timer strike breakers you all seem to praise have no limitation to the amount of work they can do before turning out to fires in the middle of the night. (possibly knackered after working all day) So please be consistent with your criticism.
I know all the crew at my local retained station very well - there's 12 of them, with a minimum of 5 available at any time. The vast majority of their shouts are 0600-2359 - we are close to the M40. They can book off (so long as 5 are still on) if they have need to stand down for any reason, without an explanation required. OK, if they get a shout at 0200 then they've not had a great deal of sleep, but they are primarily a first response asset. If anything big/complex comes along then a/more whole-time crewed tender(s) will be called for by the officer.
Best not to rubbish the retained guys here, I'm afraid, as out in the cuds they are our only chance, and my local crew have made every call for the last ten years, without fail, leaving their station in an average of 5 minutes.