Like most players in the thread are saying, its about pacing yourself. I aim for capping all of my jobs before a new expansion arrives, which gives me 2 years time to achieve that. At the start of an Expansion, it's all about completing the MSQ and leveling 1 job of each role, which i prefer to play. That way i'll always be flexible when it comes to running content. Then I focus on clearing the 8-man raids when they are released and gathering gear at the same time.

Once we're in an uneven numbered (catch-up) patch, i tend to level other jobs, focusing on the jobs for which i've already collected gear. This will make the leveling process a lot easier. Over the course of 5.0, i've cleared Eden's Gate Savage on my Sargatanas (Aether) character. But, due to the fact my Static broke up, i needed to find a new one. Since i found one was an Cerberus (Chaos) and only had a DPS Spot available, i had to level a DPS on a relatively new character (only completed Heavensward at that time) and learn the job to run Savage with it. So, i shifted my focus on that and put my Sargatanas character on the back burner.

After clearing Eden's Verse Savage on Cerberus, i got in contact with an old ARR friend who was playing on Phoenix (Light). I leveled a completely new character from 1 to 80 and got through the MSQ in 6 in-game days. Afterwards, i leveled a 2nd job (to be flexible). At the same time, i leveled 1 job of each role and all of the Crafters & Gatherers to 80 on my Cerberus character (to be even more flexible on that character).

Now, during 5.3, i got had time to focus on my Sargatanas character again and i'm working on capping all of my jobs (including BLU, Crafters and Gatherers). I'm almost there, since i just need 3 more levels on my NIN, 9 on my DRG, 10 on BLU and 5 on CUL.

This was doable, because i was running different kinds of content in between leveling (even though they were on different characters on different datacenters).