In earlier days, FIs were valued more for their experience. Attitudes such as "I will most likely have to get an FI rating after I finish all my training anyway, so I may as well do it now. Also, I am only talking about doing it part time at the weekends maybe doing the trial flights or something....." would have rightly seen you being booted out of the CFIs office and told to $od off and not to come back until you'd grown up!