Being able to "deck out" all your jobs at once is an absolutely HORRIBLE idea. Focusing on one job at a time is the way it should be or spread it out and gear all jobs at a slower pace, if that is what you want. You don't even need to be "deck out" to do Coil anyways, a relic weapon and mostly Darklight is all you need, which are far TOO EASY to get.

Also, it is entirely possible to "deck out" all your jobs without relying on myth tombs by using materia crafted gear, but you have to put some effort into it. If you're expecting it to just be handed to you then you deserves to be shot in the face.