Riblet triple vs double

[mtuutm]

We have a Riblet triple chair that goes through the sheeves for bearings way quicker then the doubles. The triple goes through nearly 10-15% more sheeves then the doubles do annually. We have doubles that run less then our triple and some that run more. Just wondering if this is normal for Riblet triples vs. doubles or if it has something to do with this lift specifically?