I don't think I've bought 12 pairs of shoes in a year. One for every month would seem a little extreme. If you buy good quality shoes for the events you need to attend, they can be expensive. However, I would hope they would last more than wearing them once or twice. "Quality not Quantity," is a good motto when it comes to your feet.
Your money is your money. If new shoes is very important to you then I guess it isn't a waste. To ME personally I would say yes, but to be fair I've have the same shoes for years and years because shoes just aren't important to me.
That would depend on the shoes and how the person who is buying them feels. In the beginning of the summer I buy several pairs of flip flops and sandals, by the end of the summer they are mostly toast.