I believe in leaving out dry, so that they can eat little and often when they want to.
Kittens need to eat a lot, as they expend a lot of energy and need to grow. Growing cats will eat more than adults, and they need it to grow fit and strong, so it is not really the time to restrict their meals.
They have little stomachs so giving them set meal times say 2-3 times a day, can mean they either wolf it, over eat and may even then vomit it up, or they fill themselves up and then go hungry until the next meal time, the result being they get less food than they require.

Most cats will self regulate, but obviously if a cat is piling on the pounds with ad lib feeding, then it is time to give it regulated set meals.