Crusts usually fall off when they are dry because when they are dry and you open your mouth to either chew, laugh, or even yawn it cracks and once the crust cracks it easily comes off as you know or it looks disgusting to yourself and others.
If you think crusts as scabs which they are then it will take you a long time to heal if you have thick crusts which are dry since cells don't regenrate at dry climates. Applying chapstick or vasaline is not advisable since that is why this happened at least to me. Applying honey or coconut oil it will heal up the process since the scab is nice and moist. Honey especially 100% has antibacterial properties which will kill any bacteria and since its PH level is acidic bacteria will not thrive. so honey is better but since it is so thick I apply it while I sleep. and drop of coconut oil throughout the day.
I don't have thick crusts anymore as a matter of fact it has been 4 days since the last peel and I don't see a crust. My top lip healed couple of days ago and it doesn't turn white under water and it doesn't feel raw and it doesn't have crusts so healed right? I think so...my lips should completely heal in a week or so...yeah so coconut oil is good and so is honey
AND applying honey doesn't make your lips or crusts yellow...personal experience so it is good