It depends on the class that you're playing.

With the Death Knight class, there are a series of abilities each on their own resource.
One spam key, can attempt to call each ability.
One that uses Frost Runes, another that uses Blood Runes, another that uses Unholy Runes, and another that uses Runic Power.
Abilities that are not on the Global Cool Down, can be called whenever.

With the Mind Freeze ability, which was usable every 10 seconds, and four Death Knight characters in the party...
That one spam key was able to call a Mind Freeze mapped key.
Which would have each character do that ability on their Step.
But with the Steps set to not advance for at least 2.5 seconds on each character.

This whole rotation worked, because it called things on different cooldowns.
So when you effectively pushed: 1, 2, 3, 4, 5 and 6...
If something was on cooldown, it could not fire off, and the next thing (or randomly, one of them) could.




With an Elemental Shaman...

Every spell you have uses the same resource, namely: Mana.
Not many spells have a recast timer, which means if you push 1, 2, 3, 4 and 5.
The ability that is on '1', is going to fire off again and again.
While the others aren't going to fire off.