Hopefully, this will help someone.
I searched for something similar and couldn't find.
Maybe some YouTube-er will create a video based on this, making the information more visible.
The experience points required for levels 52-60 are:
52: 6,186,415
53: 6,851,834
54: 7,550,331
55: 8,281,944
56: 9,051,509
57: 9,860,727
58: 10,709,135
59: 11,600,431
60: 12,535,560
The quickest way to farm experience is in 4.4.1, a sequence of 2 fights:
With a 75% experience booster and the experience masteries active, each fight gives approximately 2450 points.
Considering that around 45 seconds are needed for those specific fights (plus the map reset), let's see how much energy and time we need to upgrade.
From 52 to 53 - 665,419 points
272 fights (each fight = 2 energy => a total of 544 points ~ 7.5 full energy refills)
1.7 fighting hours
From 53 to 54 - 698,497 points
286 fights (572 energy points ~ 8.2 full energy refills)
1.8 fighting hours
From 54 to 55 - 731,613 points
298 fights (596 energy points ~ 8.5 full energy refills)
1.9 fighting hours
From 55 to 56 - 769,565 points
314 fights (628 energy points ~ 9 full energy refills)
2 fighting hours
From 56 to 57 - 809,218 points
330 fights (660 energy points ~ 9.4 full energy refills)
2.1 fighting hours
From 57 to 58 - 848,408 points
346 fights (692 energy points ~ 9.9 full energy refills)
2.2 fighting hours
From 58 to 59 - 891,296 points
364 fights (728 energy points ~ 10.5 full energy refills)
2.3 fighting hours
From 59 to 60 - 935,129 points
382 fights (764 energy points ~ 11 full energy refills)
2.4 fighting hours
