When destroying documents like junk mail credit card applications how many times would you tear an A4 sheet in half before you consider it unreadable?

You don't need to destroy the whole document, just tear off the piece with your personal information and tear it into tiny pieces and sharing them around garbage cans. And this does not just apply to junk mail, anything with any personal information on it can be used to steal your identity. You can buy shredders quite cheaply in office supply stores and I have even seen them in supermarkets (in UK). I bought one the other day for