Everything below ToT LFR is useless at this point. The time spent, especially if doing it with people of similar gear level is not worth the hassle.
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Raids last for a long time because people do progression raiding. Many hours are spent to clear a raid just once on normal, let alone heroic. Content for the majority is designed to be cleared in no time because the majority plays half an hour a week and have the attention span of a fly.
Its hardly defensible to design content that doesnt have a long shelf life over something that can last for months. LFR is cleared in a day once all wings are unlocked, and that is not even by the best, but by EVERYBODY. When a new wing goes live, just staying in the group for determination stacks promises the wing will be completed. Content that is, and this is generous, about 10 hours of time played is worthless, especially when it is used over content offering easily 10x that, over months.