Things have obviously changed in the (god! Is it that long!!) 18 years since I left.
At least in my part of the RAF we didn't have any slack. Every post noted as non-digital had privatised. We ran a nominal 4 people to fill a 24 hour post - 48 hours on in an 8 day cycle - but had to cover it when someone was sick, on a course, in the Falklands etc, and leave of course.
Not sure I'd have been impressed if one of the 4 had switched to a 3 day week and 90 days holiday a year.