How long do seasons typically last?

[HitRefresh]

I was just thinking about this since they just added like 5 new tabards for each season. That seems to imply Legion will last for 5 more seasons. How long does a season tend to last? What do you guys think about this? Is that too long, too short?

[shenoan]

I was just thinking about this since they just added like 5 new tabards for each season. That seems to imply Legion will last for 5 more seasons. How long does a season tend to last? What do you guys think about this? Is that too long, too short?

I think they generally add seasons supporting gear and achievements into the game far in advance. They might not actually get to that season, but if they do, then they already have the groundwork done.