Putting aside the function of consultant, I was referring to the role of an engineer in a particular. Normally, you have to sign your LOA for your permanent position which does not allow you to work in another company without prior permission from the management. With regards to system failure, there is another function called ISO Engineer or ISO Dept. which refers to the Quality Managament System(hence, the system failures as I put it). No, the size of company does not limit growth or function, but, it plays a role in the number of departments, etc. that the management decides on. It has to do with workload, staffing and other factors. That is what I meant by my PS.
I agree you with you different portions-experience, skills, training, etc. The basic part of "engineering" remains the same if you leave out safety to life and property(unless it is civil engineering or such). It is not common for engineers to think of safety to life and property(unless the management has included this as well). Maybe safety to life but safety to property?