On Outland EU the timer currently seems to be 15-20 minutes. Don't know if it depends on server size... It would actually make sense if it did, I guess.
Since 9am my time (5 hours) he has spawned 12 times. I have killed him 6 of those 12 times. He appears to be spawning every 12-20 minutes on Kil'Jaeden-US
EDIT: He just spawned again. 13 minutes after his previous death.
EDIT 2: another 15 minute spawn.
I really hope thats not a bug but the intended "will spawn more frequently", because if it is so then i will forgive blizzard somewhat atleast!
Its not like that on Frostmane-EU right now though. Been camping here for an hour and has not spawned.
Kamatari - Endy - Liita
US-Hellscream seems to be about 2hrs at this moment.
So apparently according to rumors its spawned once in the last 9 hours on Sunstrider EU in wich i must of missed it whilst standing in kun-lai the entire time. this feels like such a productive day!
---------- Post added 2012-10-09 at 09:27 PM ----------
LF Xrealm raid for Sha/galleon... apparently they wont spawning on my realm
US-Illidan is seeing the 15 min respawns too. Wonder if this is their attempt at keeping douchebags from not tag spreading. Hope they do the same for Galleon.
EU-Eredar 15 minutes respawn timer .. oO
I think Sha might be bugged on my server (Arthas-US). Sha hasnt spawned since tuesday after maintenance
Incoming server restarts, get ready to camp and hope he doesn't bug again.