For inexperianced people i would recommend staying well clear from G3..
In all honesty i think 90% of bodyshops should not use it, as in my opinion they use it incorrectly and do not finish the job properly.

G3 i am led to believe is a constant abrahsive, by that i mean the polishing particles do not break down.
Most other products that are availiable break down as you work them so you can get a nice finish as posted above but this will require the knowledge of what to use for what job.

I have seen bodyshops machine polish a car with G3 in less than a hour and the car looks great....that is until the sun shines on it and you can see all the buffer trails down the side of the car etc

The best advice is always to use the least agresive polish you can get away with.
G3 is one of the most agresive you can get.

Also Frenchy0204
You mention claying the car once a month, in my opinion it only really needs doing once every 4-6 months and the same with polishing.
Also i keep to 2 layers of wax and only top up if needed between polishing times.