Three months back we have built cluster with 33 nodes(AWS EC2) with each application specific key spaces having replication factor of 03

Total 33 nodes from single region US-WEST-2 multi AZ (11 nodes from RACK usw2a , 11 nodes from RACK usw2b and 11 nodes from RACK usw2c).

If we look at current load (CPU/MEM) and space usage on this cluster it's very low , so decided to decommission 09 nodes the cluster .

Now if we decommission 09 nodes later cluster will be with 24 nodes .

Question is :- Some where I read number of nodes should be in multiples of replication factor is this correct ?.

If above question theory is correct then we will end up with 08 nodes in each RACK that is not in multiples of replication factor .

Is it good/recommended to have 08 nodes in each RACK for production cluster set up which is not in multiples of replication factor ? or should we always follow the theory of having nodes in each RACK in multiples of replication factor for production set up ?