dfk41 Short answer - no, don’t worry about it if a bunch of previous cups at that setting have been good. Obviously, if you do note a recocognisable, generic issue (like a very tangy, weak cup, or a silty cup) it would make sense to adjust the grind.
The same coffee, brewed in the same immersion time at the same setting will taste a little different from one cup to the next. Whilst we can brew consistently (within the bounds of cups not being physically different enough to be accepted a such), we are making tiny drinks, one by one and perceived differences are more apparent than what we can measure & account for. I’m not talking about cups going from disgusting to nirvana, I’m talking about a good coffee being still tasty if not the best from that bag and occasional brews being particularly good. E.g. I rate my brews out of 9, a coffee that’s an 8 average might score lot of 8 with the odd 9, or 7. If it scored a 5 (neither like, nor dislike) there would be an obvious cause, like grind size change, different water, steep time etc.
With my Niche Zero set to 90, it takes about 6 notches to change extraction by 1% (minimum to start making the average of brews measurably ‘different’). For the Duo, it might take 2-3 full marks to do this at a guesstimate?