Hey! Anyone her managing a Kubernetes Cluster for a company?

Question

Hey! Anyone her managing a Kubernetes Cluster for a company?

Just a general aprox is needed for what i'm trying to do.
I want to know how much effort it is to manage a small kubernetes cluster (5 masters, 10 workers) set up with kubeadm. Setting up is fast within a day but how long does updating take approx, what are the caveats and what should be expected if i manage a kubernetes cluster?

Are there events which were unexpected for you and made the cluster shutdown or anything else?