Like Ian says (Coz he knows everything
) GG4 does take some getting used to. It's the lack of slip for the blade. The results are excellent though. Yes add more than they say.
I used Squeegee off and found it was also excellent and easier to get used to than GG4 coz there is better slip and a few SUDS
The ultimate for trad cleaning is to use Pure water and GG3 (GG3 is for soft water). I swear if you are any good with a squeegee the results are fabulous and you won't need to do any detailing.
You can buy a small RO for about £50 ish quid. If I was still cleaning and trad only after using pure for trad cleaning i would get one to make my water and stick it into a 25 litre barrel for the day mixed with GG3. For those trad cleaners in moderate to hard water areas it would be the best 50 quid you ever spent.
Andrew