lets not get toxic.

Garuda should be used for contagion due to everyone's buffs being up + foe req etc.

Then get ifrit out as with a war his damage outweighs garuda, then when all buffs are back up and ready get a contagion back out if you can manage it.

There are times when you will need to use ruin 2 more than normal, e.g. earthshakers, towers, megaflare etc, your dps shouldnt stop just because you need to move and you can not do all your movement in those GCDs; if you can you must have too much SS.

In my opinion I would save switching out for contagion for when you can fully buff your DOTs.