Teeth whitening

How much can teeth whitening done at the dentist improve in a single session?

Can I see the effects?

When you get a laminate, your teeth become very bright and almost white. Is it possible to achieve such brightness with teeth whitening as well?

How many sessions of teeth whitening should I undergo if possible?

And whether teeth whitening effects are related to age

The young person responds well, but the older person does not respond effectively.

I'm curious if it's less.