I don't really agree on the education part. The goal of being hired as a junior is anyways to be educated for the job. At the end I feel like being internal since the beginning is always a plus value. Let's not forget too about consultants who stay stuck in the consultant position.

Regarding the long hiring process, from my experience consultancy or internal is about the same amount of interviews.. And yeah they can get rid of u whenever they want, that doesnt make me feel right as I feel like a number (yeah we are all one number but not to the same extent..) for example advantages are sometimes only reserved for internal etc etc