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from what I recall, the recommended distance is just that, recommended. Apparently the optimal mfa can vary over focal distance, but I have not seen any real data to show that this said variation is of practical significance. I recall the manual recommended against getting extremely close where could be issues.
If you need infinity, I'd try 50x focal length and then go as long as you can with the test chart and see if you have any mfa variation. I would guess not, but that is why we do science experiments for critical work. Alternately, use auto focus for one landscape at infinity, then use live view. You can compare the raw images on your screen.
From a practical perspective, when I mfa my lenses at 50X, I did not see any issues with focus at other distances. Unless you are shooting narrow dof, I don't see your landscape images suffering with small mfa tolerances. I have had issues when using f2.8 - 2.0, or using a long telephoto at f4. That is where mfa can shine, if needed. So I'd repeat a famous phrase, "set it and forget it!". The bigger issue is to make sure your mfa 'sticks' during initial use. I have seen a few quirks.