I think we can pretty safely put the "Mythical 5%" mystery away after over a decade of "Secrets" revealed in books, on this site, others and YouTube. There obviously is no secret ingredient or technique. The whole issue comes down to a cook being happy with the dish they prepare.
For mine, this is mostly the case. However, I can still with all honesty say that there are often times when I do rarely purchase a curry, that I just feel they are somehow better than mine. Not just different, but actually better. More depth of flavour, and better development. Is it just the fact that they are cooked in a commercial kitchen? Or perhaps the turnover of fresh spice? (Maybe mine are a bit stale). Is it the "Ali Pan" and high heat? Is it the experience of eating someone else's food instead of your own? Is it Fenugreek and "that smell"?
Mind you, nobody complains too much about eating my curries, (other than the frequency and cream content at the moment). In my house it is mainly only me who thinks that my dishes could be improved. In saying this though, there is way too much anecdotal evidence that many others feel the same way for it to be simply disregarded as nonsense, but there is probably no clear solution. No Eureka moment to discover a single thing that has been missing.
Curry on regardless I say.