I would say that under some conditions, there really is no need to flush.
I have no experience with the mix you are using but the one I use (Agway brand composted cow manure plus humus with 40% perlite) also needs flushing rarely, if ever.
In this mix, I do the same thing you mentioned, which is feed feed feed water feed... etc. The humic acids chelate fertilizer components so that toxic salt buildup really isn't possible at the levels I feed at.
However I have to add that when you are keeping a mother in the same pot for a long period of time, even in the most perfect soil, it is good practice to flush her out, as prolonged periods in the same clump of dirt ARE likely to lead to problems.
But for potting clones into soil and then flowering them, or seedlings into bigger pots and do the same, if you know what you are doing and use good dirt and only water at the proper pH, you're GOLDEN.