"As many as the cardboard tubes they have paint for!"
I think there's some truth in that.
Just because they're showing things off, doesn't mean they have any quantity. And if it's only on display (as in a parade), it doesn't mean that it actually does what it's advertised to do.
Witness the "flying boat which can launch missiles in flight" Iran trotted out last week. Hah! It looks like plywood with a Briggs & Stratton.