Better handled regularly at a clinic than squeezed at home into scars.
Blocked pores are softened so the packed oil inside can be removed directly. The point is to clear what would otherwise turn into inflammation. Done wrongly it can leave a scar, so tools and pressure matter, and it is better split over regular visits.
It is repeated at one to two week intervals. Blocked pores keep forming, so a regular schedule works better than a single session. Trying to clear everything at once raises the irritation and can spread into inflammation instead, so clearing a little at a time is safer.