Although luck is probably the biggest factor, try to treat the maze as a well boss and try not to be too much higher than its level when you complete it for best results.
Completing a lvl 40 sized maze at lvl 70, for example will probably yield worse results than completing a lvl 40 sized maze at lvl 50. It’s pretty hard to finish such a huge maze at lvl 50, but it would work out better if you did.
Even if you maximize your odds like this, you’re still gonna be disappointed most of the time, so I would stick to starting the maze at lower level, even if it eliminates the chance of a lvl 50 or 55 map dropping, just because it’s a lot faster to complete smaller mazes.
Good luck if you continue map hunting! Most don’t
