Or you can consider

A rec B
B rec C
C rec D
C rec E


When all of them reach 60

Grant a Level
A = +60levels
B = +60levels
C = +60 levels
D
E

You will have lvl 60 character for free whenever you level each 5man team to 60

The only downside is Summon a friend of C since you can only summon 1 per hour. But you can use summon stone from lock or instance anyway. Or mage portal