I get reasonably consistent results when I want to, but I'm (overly) obsessive about removing variables.
I make a double batch of base sauce so I can maximize the number of curries I make before I have to contend with the variability of the quality of vegetables. There is of course a deterioration of flavour due to freezing but that's one variable from the infinite number of possibilities that a new batch of base sauce provides and it is easily identified. BTW this isn't a criticism of those who don't make large batches of base it's just an observation of the consequences in relation to the consistency of results.
The same observations apply for the mix powder, from a consistency point of view it's better to have a larger quantity of powder that remains the same except for the deterioration due to time. Of course the best tasting curry will come from fresh ingredients, but if like me you're still working on technique I think the consistency is essential otherwise you can't judge the results of your technique.
I make my curries at night and use the same lighting arrangement each time so that I can more accurately and precisely judge frying times on colour (and the bubble rate of course), variability of the hob's temperature becomes less of an issue but of course there's an element of experience to know what colour is good (this is something I need to work on). For anyone who doubts that lighting makes a difference try cooking bread to as brown a shade as you can get without burning it under artificial light then view it daylight. On a related note anyone who tries to judge colour from a video or picture is likely to fail

When making the final dish I have my ingredients measured out as accurately and precisely as I can before i start cooking, I even have my saucers and bowls laid out in the same order each time I make a dish

I also have a watch with a second hand on display to give an indication of the heat of my pan and adjust it to give about the same cooking times on each occasion. I always use the same pan too. I find that different pans can give very different results.
When I experiment, which I would never do before getting consistent results with a recipe first, I change only one thing at a time and decide ahead of time what that will be. Knowing what changed the quality of the end results is then trivial.
I expect that the reason the chefs don't taste the individual dishes is that taste is too subjective an assessment to be useful, as spiceyokooko pointed out: "Your taste buds would probably be frazzled to the point you couldn't taste jack shit."
For the record I'm not a great cook but I know a variable when I see one
