They usually swap between these 2 events.

This one is good for those who close to Adv Refine to claim rewards and be ready for next Limited Refine.

You can either hold on your med refine or use them to claim rewards..

Hi there!

The time limited refine event will be back in the future :) we just don't have an exact date for it...

Thanks for your enquiry :)

There are situations where limited refinement is better and situations where is not. Lets say you have a rank 7 item you weren't able to level up when last limited refinement was up (like happened to me that i reached 188/200 that, after the event became 138/200 due to the disappearing of the wish credits). In that case you want to get the advantage of the fact you c*e medium refinements on other items to get 20 free adv.runes. If you do it two times, without leveling them up (lets say bringing 5 level 4 from 0 to 20 and 3 level 5 from 0 to 34) then you can get something good out of both without losing anything on long term planning. But, yes, personally i think the rewards from that rebate are a bit low. 2x as many should be more appealing.