They did not use additional liquid sealer at the factory but you can if you're fast enough. This is a two-person job. Yes, experience helps a lot.
Basically, both guys set the glass WITH the moulding and rubber intact. One guy reaches inside and pulls on the ropes while both guys slap the glass into position. You may use a third hand to pull the rope out from inside the car.
This slapping procedure is important. I needs to be hard enough so that the glass 'beds' itself both in the rubber AND the rubber centers around the sheet metal body. If slapped too hard, of course the glass will break, but that is unusual. The rope simply pulls the rubber 'lip' over the body metal while the slapping process sends vibrations which seats it all together.
I saw one yahoo at a glass place, cutting the flange off the moulding. He didn't realize the stainless goes into the rubber BEFORE the glass is set. It's in the Shop Manual.