We've decided to remove the global/settings based OperationTimeout. It was simply using a cancellation token with a timeout baked in and didn't provide as much granular control as is probably needed for this type of setting. In addition, a client-side timeout like this doesn't alert the server of a cancelled request.

Hence, for timeouts, using maxTimeMS in the places where it's supported is the better alternative. When client-side timeouts are needed, writing a WithTimeout extension method is trivial.