"Sacha" wrote
snip
I think quite a lot of people plant trees because a friend has one or
they've seen it somewhere in a much larger garden and want one
themselves.
In my old house there was a young blue cedar and I had the horrible
job of cutting it down because it was much too close to the house and
when it was fully size, would have prevented anyone getting to the
front door!
That had been planted because the people next door had a much larger
garden and had a blue cedar planted well away from the house but in
line of sight with mine. I can only imagine that the original planter
thought that two such trees fairly close together would one day look
magnificent. But their thinking obviously hadn't gone further than
that.

Another reason gardeners can get choice of trees or spacing/position
wrong is misleading info when they do look for advice. One thing that I
blame is the tendency of some plant labels, and often also books, to
give the height and spread of trees and shrubs as a rough size *after
ten years* but neglect to give any idea of mature eventual size. The ten
year bit isn't always stated, either.

--
Sue