In article , Kay Easton
writes
Snipped
If they are 20 foot now you should be able to take off about two foot, then
in three or four months
take another foot off.
I took 9' off my neighbours in one go without any ill effects and the
trees continued to grow

Then you will be looking at taking new growth off every three months.
Only during the summer of course

And it doesn't need to be that often. Ours has about two foot of green
growth horizontally, so I could cut it back at least a foot with no
problem. Though if I kept it trimmed back, I suppose I might have a lot
less, and would have to trim it more often. But I'd sooner trim a nice
soft leylandii 3 times a year than a hawthorn once a year!

Agreed and as I have said before I find the Laurel much more of a task

--
David