I have Ivy growing along the side wall of my garage - I planted it when the
house was new and was desperate for anything green.

I now want to reduce its density but find on cutting it back I am left with
just a backfill of old dead leaves and tangled branches.

Should I really go for it and cut it down and let it regrow, resolving not
to let it get as bad? Or should I thin it right back to the wall and thin
out some of the tangle of branches?