ofc there are many playstyles but CDR always will be better than RCR especially for speeds and in gr. When u feel u have more CDR than u need it u can always switch zodiac to other ring (eg. F+R) or roll dmg into rings, gloves, shoulders, weapons or even vit/loh what u feel u need the most.
Theres always gogok - so there are many ways for min-maxing.
However, easiest way to do t13 under 4 min is doing it in the group