Then you begin to realise why rear mech hangers exist and sacrifice themselves when necessary.
It’s a favourite pass-time to blame a part like a gear hanger for an incident. Think twice. When the gear hanger bends or breaks under load it is paying for our riding environment, riding habits, lack of maintenance, mechanical sympathies and everyday abuse, so expect it to break at some time and carry a spare. With the best will in the world, what we plan to do as sympathetic bike owners with the up-keep of our bikes, tends to fall much short of our actions.
One more thing; mechanics get it wrong too! Just because the local LBS replaced your recently departed gear hanger with a fresh sparkly new one, it doesn’t mean that under pressure they diagnosed a fault at all, that they diagnosed it correctly or that they ensured they had used a DAG tool on the new hanger they just fitted before sending you home with your bike.
Time spent differs hugely from one LBS to another. If an LBS needs to diagnose why a gear hanger failed, expect to pay for labour time to do it. Its not just a gear hanger fitting charge. Given the nature of a gear hanger breaking, expect potential replacement parts from time to time too.