Thanks for finding this, certainly seems like it merits discussion.
I would suggest that the first two might indeed be duplicates, in that both ask about whether one can become a professor without overworking. Indeed, the first one has already been flagged as a duplicate of the second and is still working its way through the close-vote queue.
The next two seem to ask a very slightly different question, about whether it is normal for professors to work long hours. I see this is a bit different than the previous group, since the previous group wants an assessment of a particular strategy's viability, while this one seeks a measure of normalcy in the current state of practice. As for whether #3 and #4 are duplicates of each other: it does seem like they "boil down" to the same thing (working hard), but #4 focuses heavily on the "family" and "holiday" aspects. This is reflected in the answers: #3 agrees that long hours are typical, but #4 says that working over Thanksgiving and neglecting family is not really normal.
Similarly, five and six ask about long hours for PhD students, which makes these two distinct from the other four. In this case, #5 is about whether long hours are required to be successful (similar to #1, but for PhD students rather than pre-tenure professionals), while #6 asks about whether it is abusive for an advisor to demand long hours. There is also this question, but it has a flavor of "how can we change it?" At an earlier stage, we could have edited these questions to avoid rehashing the long hours discussion, but at this point, such an edit would invalidate the existing answers.
TL;DR: I think #1 should be closed as a duplicate of #2. The others do have some overlap, but I don't think they are close enough to be retroactively closed as duplicates.