(Question) Tooth whitening pain and effectiveness, I'm curious.

Recently, I have been 고민하다 between laminate and teeth whitening, and I think teeth whitening might be simpler and safer, so I am looking for clinics online. I noticed many places offer teeth whitening promotions. However, prices vary greatly depending on the clinic, and some offer same-day or package treatments. Is teeth whitening not effective enough to be repeated regularly? I also heard that the results vary depending on the individual, and I am very curious about what criteria determine these differences. How long do the effects last after a single treatment? I heard there might be sensitivity; I wonder if it’s similar to the pain during scaling or worse, and whether there is a risk of persistent side effects like ongoing sensitivity after the procedure. Are there any foods or activities I should avoid on the day of the treatment or for a certain period afterward?