Best to wait till new shoots appear from base in spring and then it can be pruned hard back. I do reduce mine a bit after flowering, however, just to keep it from whipping around in winter wind.

Yes - I cut mine halfway back, as I lost one in autumn gales when I didn't bother. Then in the spring, really hard back. Mine has grown about 10 ft from the base this year.

I do that too. The wood is quite brittle and if the branches are very long they can snap.

The whole shrub went, Steragram. It just ripped apart!