I usually only have one pair of shoes on the go at any time, and they tend to last me for years. My wife buys maybe six to ten pairs for every pair I do. The reason I felt a need to buy a new pair was because of a gash in my old pair.
I think I did it when moving a three-piece suite out to the front of the house, ready for the council to take it away and shred (for £70). A passer-buy asked if he could have the sofa so his kids could play on it, so I said yes; even if I knew in advance that there'd only be two armchairs to take away, it would still have cost me £70.
The gash serves to show two things: firstly, people who don't wear shoes can expect the occasional visit to the accident and emergency department of the local hospital; secondly, whatever they make shoes out of these days, it's not as gash-resistant as leather.
I've only shown you part of the shoe, so it's harder to notice that I don't shine them as often as I perhaps should.