But my vehicle glass guys hate it because it makes it really hard for chip filling plastic to adhere to the glass when I get a rock chip on the windscreen. Rain-x is a contains polymers that bond with glass crystal structure to form a hydrophobic (water repelling) coating on the glass. I use it on my car windows, and water just beads up and runs off so I hardly have to use wipers unless it’s a real downpour. If I had a glass shower that’s what I would use.
You have to make sure the glass is completely clean and dry. Then apply Rain-X and buff off excess with a paper towel. You’ll be amazed at how water beads up and pours off. If you have a good, clean, undamaged squeegee, you should be able to quickly squeegee off the glass. It will wear off eventually, so you’ll have to renew it every 6 weeks or so. YMMV depending on how hard your water is.