There are only a dozen cards I currently use daily in rank battles. The thinking I have now is that I am going to concentrate on staking higher levels for these specific cards. I am planning ahead in the near future the game will switch into new reward cards and as of now I want to be realistic with my expectations.
In my past series of reward cards I was able to max rare and commons but I don't use many of those cards either. If I focus on specific cards that I use the most I may have enough time to stack epic and legend cards. There would be better odds of me getting higher value cards in epics and legend if I have more time stacking those cards.
There is little use of my common and rare reward cards that I will continue to focus on stacking epic and legend cards. Another sign that I would be on the right track if I am able to stack accordingly.