The pack must adhere to the set time.

In my case, I also leave the face mask on for longer than the set time.

For some reason, I feel like I could get more nutrients if I keep them on longer.

however..

It is said that leaving a face mask on for too long can actually cause moisture to evaporate into the air, leading to dryness. It is recommended to stick to a time of 15 to 20 minutes.