If guests keep returning to the park, but then don't spend at F&B options, that's measurable. They do need to chase a return visit. Alton Towers need people to keep coming to the park. Aramark need people to keep purchasing F&B. There's a finite pool of customers and they can dwindle away, or vote with their wallets. You may end up with a situation where the park is at capacity, but F&B revenue is shockingly low, at which point questions should be asked. Profit margin is all well and good, but you actually need to sell stuff to be able to see those profits.