Mine (DD1 13, DD2 11) get a pound a day each. They get paid monthly, when I get paid. From this, they have to save 20% and they march into the bank with their passbooks quite happily.
From what's left, they can spend £2.50 max on sugary crap or Doritos or whatever guff I won't buy.
To be honest, the first few months they blitzed, but slowly and surely, they're starting to click, and DD2 particularly is hanging onto her dosh and budgeting for the month.
If we go out to movies etc I pay, but from 'their' money they are expected to buy any clothes they particularly want - I'm responsible for uniforms, basic jeans, trainers, etc, but that £12.99 top they love love love? Their money.
They also buy gifts etc from their cash, along with nail varnish, books, etc, and their savings are spent on holidays or on long term goals like laptops (DD1 bless her has £45 in her laptop fund, it grows by £2 a month at the moment)