I donīt believe that a guy with this type of question is really flying a jet aircraft, on the other hand, I reckon that you always need to have enough fuel to proceed to your alternate, because itīs possible that something (like an accident) close the airport/runway
And what happens if you divert and it's the diversion airport that suffers the closure? Is your alternate statistically less likely to close?
Where's common sense in all this?
You are flying to airport A with one runway and your alternate B has one runway. The wx is CAVOK in both. It's busy in A and you have 10 mins of holding fuel. Your EAT is in 15 mins. You get to 10 mins and divert, just in case someone blocks the runway at A and you have to divert and arrive at B with less than final reserve. But on the way it's reported that someone has blocked runway B. Oh dear...
What I can't understand is the lack of logic that dictates we divert to B and land with final reserve fuel only or stay at A and land with final reserve + most of the alternate fuel.
Unless you have statistically proven that the alternate is less likely to suffer from tyre-bursts etc than your destination, in which case you need to inform your local CAA and apply for a stats degree.
Clearly the command process at so many carriers is not producing those fit to command.