In reply to Andy Nisbet:
I like to place 'em diagonally. Having said that, I've placed loads side by side. Started off placing them (staples) one above the other (didn't know any better, not so much information around then, even 12 years ago - no Dan, for instance!) Those aluminium ones though... they weren't much cop. Only joking!
Being honest, we've nearly all occasionally top-roped directly. Occasionally, I don't mind. But when people do it all the time, I do mind. And, at a very popular local crag (The Cuttings), an awful lot of people do it all the time - not maliciously, just thoughtlessly.
A bit more thought, a bit more care...?
Mick