“cost of error” 100% - this is the big driver for me and important discussion with Client.
The flip side, is the cost of trying to control the process - if the client has always had “free form”, trying to hardcode a journey can involve errors and bugs.
Blueprint is a great way of mitigating this but you may want to have a balanced approach between free form and guided journey’s if the client is transitioning. Having been an SME in a long past life, we tried to build guided journey’s - if I had my time again, I would have built in a little more flexibility for those “edge cases”.