There is absolutely no reason to go from 5 to 10. Med refines are easy to come by anyway.

From 7 to 8 you need 200 adv refines (-50 from wish credits)

From 8 to 9 you need 500 adv refines (-100 from wish credits)

From 9 to 10 you need 1000 adv refines (-200 from wish credits)

So in total you need 1350 adv refines in worst case to go from 6 to 10.

Answered by someonerandom . As i asked the same question a while ago.