Q:
Difficulty Scale vs Reward Level - Fractals
No, you can;t just leave halfway through to advance to the next level, or get the end chest/daily reward.
Odd # levels will have 3 instances, (1-3-5-9 etc), and even ones will have 3 + bonus stage which is Jade Maw, after killing him you get a chest, and if it’s your first time doing that level bracket for the day you will get a daily reward which can give you ascended rings, more relics, or a fractal skin.
(1-9)(10-19)(20-29)(30-39)(40-49) are currently the completeable brackets.
Your personal level increases at the end of the 3 or 4 fractal’s. Quitting half way doesn’t advance your personal level.
In Hoc Signo Vinces
The difficulty scale means how hard the dungeon is. Mostly, it deals with number of mobs, level of mobs, and the intensity of agony. (Agony is a debuff that only occurs in fractals and can be negated with a stat called Agony Resistance.) You cannot open a higher level fractal than the highest level someone in your party has completed. For example, if all the guys in your party have never been to fractals, you will only be able to open level 1. If one person in your party has completed level 10, you can open any level up to 10.
Personal Reward level is how much you get rewarded. I am currently at level 26. If I go do level 10, my rewards are a little better than those who are at level 10. Likewise, if you are level 1 and you do level 10, you only get level 1 rewards. Your personal reward level is also the max level you personally can open.
To up your personal reward level and the max-level you can open, you have to complete a fractal either the same level or higher as your current level. A complete fractal run is all the fractals Dessa sends you to until she brings you back to the lab. As the people above me already said, odd levels (level 1, 3, 5, 7, 9, etc) are 3 fractals and even levels (2, 4, 6, 8, 10, etc) have a 4th bonus fractal that is always Jade Maw.
Sea of Sorrows