Putting black hole on top of your wax? You could do that and it will give it a nice freshlly waxed look ( which it techinaly will be) but what you will find it that with a good wash routine you will mantain the look until the wax has done its job and starts to fail.
You could do the full lot every six weeks if you wished but you would get away with it for a bit longer than that. If its natty thats the last lsp on then i have seen that last anything upto 5 months before needing stripped off and a fresh wax coat applied.
Is it autoglym bodywork shampoo conditioner your using? That is ph neutral as you say so it wont strip your wax but I know that that specific shampoo leaves a coating of its own on the paintwork. This isnt a bad thing and may people dont really bother about it, just means that the water behaviour of the shampoos coating probably wont be as good as the wax gives. This layer will eventually wear off and the wax will come through and show its version of sheeting and beading.
As for a weekly routine i would just snow foam ( if you have a snow foam or a pre wash) , rinse off, snow foam again but this time using a soft brus to get into the little gaps, wash the alloys and tyres, then move onto the body work using your choosen shampoo. The only thing i really apply is a tyre dressing.
What colour of gt is it you have?
Hope that helps, might have got a bit carried away with my reply, sorry about that