I keep all my cigars at 65% including CC's and have always been pleased with the results. I used to have them at 70 when I started out and had bad experiences. At 65 I rarely ever need to dry-box cigars to get full enjoyment.
The theory runs that you try to match your smoking areas humidity to reduce cracking when making such changes. As little as 5% has been theorized to greatly reduce cracking.
That is the theory I've heard others throw around anyway, I personally keep mine at a steady 65% year round.