My friend Lisa from Chicago tried air frying Brussels sprouts last week... she cut them in half like you said but dumped the whole bag in at once. They steamed instead of crisping up, came out soggy and bitter. I told her about the overcrowding thing, so she tried again with just a single layer. Night and day difference, she said they were crispy and almost sweet. Now she's hooked and experimenting with carrot fries too. Her kids actually ask for the crispy sprouts now, which is wild.