Here’s a bit of back-of-the-envelope math. Consider the Race to World First. Guilds vying for first place in the RWF will typically raid for about 16 hours per day, with no breaks until the raid is cleared. The race usually takes about a week. There’s a lot of variation, of course (Sepulcher was a sh!tshow), but the typical RWF completes in 8 days, being cleared shortly after the first weekly reset. That’s 16*8=128 hours of raiding to get the kill.
Compare that to a typical twice-a-week, 3-hours-a-night raiding guild. They’re raiding 6 hours a week. If it takes them about 128 hours to clear the raid on M, that means it will take 22 weeks to clear the raid. That’s assuming you don’t have to cancel raid nights because of holidays or whatever. That’s a ton of time. So a simple observation: RWF teams complete the mythic raid 22x faster than a normal raid team in large part because they play 22x more hours per week.
People might object that the raid gets nerfed over time as you get better gear, so it should take less time for normal raiders to clear the raid on mythic. But I don’t think that people clearing at the end of a tier are taking substantially fewer attempts on the end boss than the RWFers are. The fact that normal raiders have better gear by the end is balanced by the fact that:
- Most guilds spend a few weeks in heroic first to gear up. RWFers do that during heroic week running splits.
- People in normal guilds aren’t the very best raiders in the entire world.
- RWFers kill all the M bosses once or twice on the way to Cutting Edge. Regular raiders will do it a dozen times for the gear. (And if one guy who was running seeds on Xymox has a baby and has to take a couple months off, you’re back to teaching a new guy the hardest mechanics and you lose two weeks when you should be working harder bosses.)
When tuning the raid, Blizzard should have a goal in mind for how many hours, total, it should take for a team to complete the raid. The % of players who will complete the raid is the % of players who will have that many hours available to do it. “Weeks to clear” isn’t the relevant metric. It’s “hours working prog to clear.” What, exactly, that goal is is up to the devs and depends on the kind of game they want to make. But if your raid tier will last X weeks, and it will take more than 6X hours to clear the raid on M, clearing the raid on M will be simply out of reach for the huge majority of your players.
Many teams raid 3 nights a week in order to get the clear; 9 hours a week. If it takes more than 9X hours to clear on M, clearing on M will be simply out of reach for almost everyone (see, e.g., Sepulcher).
Bear in mind that 6 raid hours per week players aren’t playing for 6 hours a week. They’re doing dailies/WQs, M+ for their weekly chest, maybe some professions or achievements. 6 raid hours a week isn’t casual. That’s the dedicated player base who wants to do difficult content. They can’t, though. Because it takes too much time.
The problem with mythic raids - the problem with sepulcher - isn’t really difficulty. It’s hours.