...with the gravy, simple is better. You then add fresh garlic, tom puree and spice etc.. to enhance the flavours already there and give the curry a fresh, just cooked taste. The final curry to me is were the magic happens, happy currying 
I agree with this, too. I'm sure the skill is in the mix of spices added to the final curries. The base sauce is best left bland to allow it to be used for almost any dish, without everything tasting the same or too hot. Everything you read about Indian cooking suggest that the skills/secrets are in the precise mixes/blends of spices used - some handed down over generations, or mixed in secret at home by the head chef, if some stories are to be believed. The vast number of permutations and combinations of spices which are possible, gives a mind-boggling number of choices for the spices, which is why we may be 95% there (to the BIR taste) but not 100% for every dish. I recently listed a few dozen options for the way fenugreek alone could be used. Any spice can be used whole, ground, plain or roasted, added at the start of cooking, in the middle, or at the end (like garam masala). All this, for dozens of spices, gives more combinations than would face someone trying to break into a safe. It's so disappointing when fraudulent authors purport/promise to deliver recipes which work, but in reality they don't.
Regards
George