Actually once you have clean the paintwork,you can use normal wax say once in 2/3 months. In between your wax session, apply spray wax after every wash.

I'm using Gyeon view, so far it's good but I won't say it's really amazing and not very diy friendly plus it's not cheap (currently RM3xx for the kit). 3 months in and it's still holding up but speed below 80kph(maybe my car's aerodynamic is not good enough)needs to use wiper and if you follow other cars on the highway, it will be less effective (perhaps slipstreaming). Also need to learn not to keep using your wiper or it will significantly shorten the lifespan of the coating.

I think it might be better getting a very good pair of wipers such as PIAA silicone wiper and etc. I have a few friends that are using PIAA and good feedback overall. (application needs to pay some attention in cleaning, will affect how good it performs) But one caveat is silicone wipers can actually scratch your windscreen slowly if you always use it dry/not wet enough.

Don't try to use Rain X or cheap coating on your windscreen, it's not worth it, fails very quick and the residue may affect your wiper performance and visibility after that. However they are pretty good for side windows )

Hope this helps.

Soft99 ultra glaco (the latest)  so far so good, 6 month apply once, without any problem, no wiper jerking or anything, make sure u clean and polish ur windshield nicely b4 apply, price is super cheap, up to 10 windshield i think