Hello,

The series of quests you refer to are not meant to be challenging for someone who is Level 50. Yes, they were completed quickly, but do keep in mind that it was completed by people who are already level 50 in all their classes.

Should anyone who is not level 50 already (including all new adventurers and those who have yet to train those classes), then such a feat is not possible, as it would require them to level from 30 to 50 as well.

If one keeps in mind one can only progress every 5 levels, then it is not a 'fast' feat that is easily accomplished.

Fortunately, for those who still seek challenges, there are many out there. Of course, most challenges can be solved by throwing as many BLM as you can find at the problem. But if you choose to not take that route, then a challenge shall await you.