I think there are "claims of no leaks" , but if your car is garaged or you have all the interior panels in, you are just not seeing the leaks. That's why there are troughs inside below the front, rear window, then drain holes that drip into the side and the more drainage holes.
Put some black silicone in the gasket channel for the glass, put the gasket on the glass, then, here's the the secret, use KY or some other personal lube, yes it's funny, but it's water based, Very important, in the windshield frame channel with a small, 1/8 rope stuffed in the channel with the ends on the bottom. Temperature should be above 70 degrees so that the gasket is soft.
Learned this from my dad who still does it this way, takes more time to get everything ready than to put the windows in. Takes about 10-15 min on the front, about 5-10 on the back...sedans (Biscayne,belair) put the top of the rear glass in first.
Never smack the glass, hit it in any way, or use any metal tools. One person on the outside holds the glass...really easy to do. Let the KY dry. Then stuff the sealer in, again only with plastic tools. Oh yea, did you put caulking around the trim clips before you put the window in? Make sure to fill in the holes.
It's harder to do the ones without a gasket because you have to be careful not to smear the rope seal or put fingerprints on edges.