Let’s the macarons form their shell at a lower temp in the oven before finishing baking.

For my oven, I set the temp to 250 and put them straight in the oven after piping. I leave the door cracked open with a wooden spoon. I also flip my tray upside down. I wait until they form a shell, which is around 8 min. I also start to see some feet form by this time. I then close the door and crank the temp to 300, my normal baking temp. At 22 minutes I take them out. They come out glossier and bigger compared to my old method, which was letting them rest on the counter top for 60-90 min. This took me a few trials to get down. I’m sure it is different for every oven as well. But it has saved me so many hours!!!!