"He does not run in the long run."
In the long run: after a long period; läuft er nicht: he does not run. This person is probably like myself. i once started running every evening. After about 3 moths I gave up. I did run, but not for a long time. Further i would sau "Auf die Dauer", but that is probably not the sole translation.
So how is this communicating something different than "He does not run" (ever)? Is it "He generally does not run"? English can use the past tense for many things that German uses the present tense for, so I'm not sure how your sentence "seen over a long time he does not run" means anything different from my "He has not run in a long time".
(I'm not trying to be disagreeable, I really want to understand both the meaning of Dauer and how these verbs/tenses are used differently)
Ignore the Duo sentence for a minute (poorly worded in English in my opinion). Try this sentence. "It doesn't pay off in the long run." If you invest money in his company, there will be some gains and losses, but you can be sure that when viewed over the years, you will lose money. "It doesn't pay off in the long run". I don't think I would ever say "He does not run in the long run" unless I said "Arnold keeps saying he is going to race in the Boston marathon, but I bet he does not run in the long run." I don't think I would use it in siebolt's example of giving up running.
I hope I didn't make matters worse. I had to comment because the English sentence bothers me.
You are correct to make a comment, the English sentence is poorly chosen. Wouldn't it be more natural to use "in the long run" for something that happened in the past or something that will happen in the future? For instance, "He didn't make it in the long run" or "He will not make it in the long run."
OK, I think I understand this, though it's a very odd sentence to give us without another sentence or story as context. I am having trouble translating. Perhaps the best I can do is "He isn't likely to continue running over the long run" (it needs the hedge of "likely" or something similar because how can the speaker know? it's a prediction). I think a critical part is that the English sentence would use "over the long run" (as would the sentence about investing money) not "in the long run".