Columbina needs more CR than I thought

I had been under the impression that columbina only needs 45cr in a on-field team with lauma because lauma+10cr, bina passive +15cr and the dps set gives 30cr but, when fighting the abyss dog this stygian with this team I noticed I'm missing a lot of crit. Enough that it was a problem. Which made me realize that bina passive at c0 can only give you 5-10 cr at all time because of how every stack depletes after 10 seconds independently from the other stacks. Why then did every guide and youtube video at the time tell that she gets 15cr from her passive. I realize It's mostly my fault for not thinking it through at the time before building her and taking what was said to me at face value without thinking it through but it's funny how the people can be driven forward with false info and it would be so hard to stop them and correct until it's too late.