That’s exactly what I do, I’ve still got the stock oldschool Azu/Gunfisk/Altaria line-up, because it generally gets me to R20 by the end of the first GL and then I can ignore it for the remaining 2.5 months, bar any quest related requirements. It’s one of the things that put me off PvP is that not only is it not that fun, but I don’t think it’s that efficient as a dust gathering method unless you play it regularly, plus a random rebalance can render that great investment of an ETM and 150k dust just another option at the flick of a niantic switch. But I suppose that’s the point, in the same way that grinding dust by catching is more profitable, if you catch more stuff, but catching Pidgey number 2376 and the 100 dust it brings isn’t exactly the high octane thrill of a lifetime.
I’m surprised I’ve not seen higher figures for dust, albeit only a few people have replied and @stativision has a decent chunk. It does, I have to admit, likely seem to be a solid method of farming dust without leaving the house, plus if you enjoy it, as most seem to, a free way to play over a long period - it certainly lasts longer than the 2 free raid passes.