Serious question, my sister says preheating the air fryer is a scam and now I don't know what to believe
My sister came over on Sunday to help me move a bookshelf and we got into it about air fryer preheating while I was making frozen fries. She claims she never preheats hers and the fries come out the same, saving about 3 minutes every single time she cooks. I said the manual on mine says preheat for 3 minutes at 400 and I figure the company knows what they're doing. She shot back that manuals just cover them legally and that half the recipes online preheat out of habit, not because it does anything. Then we tested it, one batch in a cold basket and one after a 3 minute preheat, and honestly the preheated ones were crisper on the outside but the cold ones were done almost 4 minutes sooner. Now I'm second guessing every recipe I've followed for the past year. Does anyone here actually skip preheating on purpose, and if so what foods does it work for versus what foods it totally ruins?
My grandma went through this same thing with her old toaster oven back in the day, swore up and down that preheating was a waste of electricity and she'd just toss stuff in cold. Then one Thanksgiving she tried that with a frozen pie and the crust came out soggy on the bottom while the top got burnt. So she went right back to preheating after that. The thing is though, a toaster oven and an air fryer are kinda different beasts because the air fryer moves heat around so fast. Your test actually makes sense to me, the cold batch finishing sooner but coming out less crispy tracks with how these things work. The heat has to build up in the basket either way, so you're just trading time for texture. I'd say for something like frozen fries or nuggets where you want that crunch, the preheat earns its keep, but for leftovers you're just warming up, skip it and save the minutes.
Learned this the hard way with chicken wings last month. Tossed them in cold thinking I was saving time, and the outside got nice and brown while the inside was still pink. Had to put them back in for another eight minutes, so I saved zero time and ate late. My sister just laughed at me because she always waits for the beep. Now I preheat for anything raw but leftovers like pizza or mac and cheese go in cold, no problem. That grandma pie story is basically the same lesson with more tears.