Great thread, I would like to add my own experience. Not very interesting but may be of interest from a non-arborist point of view.
I managed a 300 acre beech woodland on the north downs for nearly 20 years. The site is well used by the public, being both a public open space and Local Nature Reserve. The woodland was hit hard by the hurricanes of 1987 and '91 with some compartments losing 100% of the mature beech.
Those trees that remained had, in the main, sustained some damage from falling adjacent trees.
My intention, at that time, was to retain as many of the remaining mature trees as possible. This meant managing the public, rather than the trees. It was important to be able to move paths away from trees in decline, standing dead trees and those with suspect limbs.
Now, the point I'm labouring towards here is; many remaining trees became hosts to a variety of fungus, with meripilus being particularly obvious. Of particular interest were three large Georgian boundary trees ( I will include pics when I can find them) all within 50 yards of each other, each with large merip bodies around the base. One of the fruit bodies so large that it became of local interest.
These trees are all situated on thin soil above chalk. There was an adjacent bridleway (later moved away from trees). However only one of these trees failed, the other two remaining are there today, with merip fruiting regularly.
The merip fruits are however, declining in size due, I suspect, to the reduction of available nutrient material.
The way I see it, having watched this woodland over many years, is like this; trees are like people. There is not one panacea that suits them all. All the trees growing, growing in the same medium, affected by the same pathogen are not going to behave in the same manner, despite the fact that they are all connected. There can only ever be a general rule in terms of its physiology etc..
Unfortunately, few people/organisations are prepared to throw cash at tree retention/ preservation allied to the knee jerk reaction that follows H&S in this blame riddled culture we now find ourselves operating.
Now, in 2005, I left this site and now inspect trees across all our sites and my desire to retain old trees has waned somewhat. I now suffer from a little known psychological disorder known as Tree Paranoia and willingly condem a tree where the target is immovable.