Our progression attempts must look funny to the people camping outside the instance , the guilds that stream past them in ghost form as they wait patiently.
Sometimes when someone is still alive inside my instance and we hit the instance wall with the message that an encounter is still in progress ( don’t hit it too high in Ulduar cause then you die again) I get a Glimpse of the members of the guilds waiting. Horde and Alliance, facing the instance whirl. Some are roasting marshmellows on campfires, others are jumping around, or dueling.
I know guilds have different rules, but I will never be in one where they make you wait outside the instance on your toon. Hoping for a chance to get a spot in the run. The Best alternative I’ve heard of is you park your Toon outside the instance,you are able to play an Alt, but you are to remain in the Vent channel to listen out for the swap request.
I think to make someone wait outside the instance for 1 hour, 2 hours 3 hours without other forms of entertainment is cruel, and really makes raiding a job and not fun. Maybe with that attitude I will never be in the top progressed guild on a server and maybe that is what it takes, to have your reserves waiting outside the instance on the offchance that there will be a swap and you will get to raid. Is that extra 30 sec’s it is going to take to at the very least swap over toons on demand really worth torturing your members so, and how often would you actully swap people in and out for, and who would you swap – even now when a Tank can become a DPS or healer with the flick of a Offspec Switch
Provided by 
Pugnacious Priest's Warcraft Blog 
I’ve never understood this either, especially on a PvP server you’re armor will need repair before you get in.
If the raider is parked their, ready to go, let them go play an alt but stay in vent. It’s not that difficult you’d think.
Since warlocks can summon people in the instance, it’s completely strange that any guild requests real camping outside. It’s enough to be online.
Guilds actually do that? And here I thought it was just a bunch of horde pricks waiting to AoE down an unfortunate raid group that doesn’t get into the instance.
With the new “anywhere queue” BG option, one could always do some PvP. Then it’s just a matter of /afk out and zone in.
Though I also do not understand the requirement. I’ve had a guild ask me to stay in a raid (though I didn’t have to stay at the portal) – this was almost MORE annoying, because I couldn’t do dailies while in the raid.