The IAA is run by accountants. Everything is a 'business'.
A manager explained to a controller that as a stand alone business, Dublin centre lost money, so costs must be cut. The controller pointed out that if it was a business that lost money, it should be shut down. To which the manager replied, 'but you can't do that!'
Apply the same philosophy to the current staff shortage. Supply and demand. Let the market decide. Hold out for the best possible deal.
Applied to leave - wait until there is a guarantee of a minimum amount of leave to all staff per day (within reason of course!). This includes Annual, Parental and Maternity leave (the only guaranteed leave at the moment together with Sick leave!). Maybe even hold out for some of those 'family friendly policies' like Job Sharing, Career breaks and Unpaid Leave.
Applied to Working hours - wait until rosters are guaranteed to be no worse than they currently are and that fatigue breaks are always applied in every station.
Applied to overtime - wait until the price offered for your services is so high you can't possibly refuse.
Remember were the vast majority of the IAA's revenue and profit comes from.