User blog comment:Amphitere/Amphitere's Skilling/@comment-74.240.184.162-20131101001736/@comment-6053607-20131210201445

To add to Amphitere's post...please note that you can always increase the card level as long as you use a card (skilled or non-skilled card), as long as it has not reached its maximum card level.

On the otherhand, it is not always guaranteed that you can always skill up the card skill level by using skilled cards. The higher the card skill level, the more difficult it becomes to skill up. I've had plenty of experience failing to skill up at a high 90%+ success rate (I failed at 98% - go figure). The only way to guarantee skill up of your card skill level is to make sure you have 100% success rate.