And lets not kid ourselves, this is a numbers game for us, just as it is for the bean counters.
If every flight was planned to land with 3 hours fuel, there would be no diversions. If every flight is on such bare minimum fuel that if the forecast winds are 1 knot off we have to divert to the Refile, then there'll be a high percentage of diversions.
The middle ground is where we all earn our living.
If management, correctly choose to increase the likelhood of a diversion by reducing planed fuel over the destination, then our job is to agree yet to preserve "Safety First" we therefore move the diversion point further back into the flight. No big deal; And as with ETOPS, having done all the sums and all the planning, SOMETIMES a big twin will find itself in Cold Bay or Midway. Big deal.
Never, ever, ever hold til the only option you have is to hope that the recently improved conditions stay better.