In general it depends a lot on where you operate. Unlike Meikleour i have never experienced a blocked runway (except for weather reasons, snow/ice/freezing rain) but plenty diversions due to weather, and i'm just two countries further in the middle of europe. Using statistical contigency fuel, which we we don't use in most cases, that alone is enough to not just go to the closest alternate, but chose from two to three different ones. Yes, theoretically we can plan without any alternate (if weather permits), but usually that requires a bit more fuel than simply going with one, and even than we can choose between a fuel alternate or more commercially/operationally fitting ones. Europe has an airport density that is simply more than enough for that. In more remote areas that is of course different, and as said above, if one flies a super, the number of available alternates dwindles quite considerably.
As usual, aviation cannot work without a certain flexibility on the day, and everything depends on where you are, where you are going, in which kind of equipment, in which conditions, both enroute and at the destination.