Yes its a personal opinion. Nobody has anything else here.
If instructing is a vocation for you then it is my opinon that you should charge for your services so as not to dissadvantage the majority of FI's out there for whom it is a job. Or instruct in something like the Air Cadets on a proper voluntary basis.
That said the profession is immeasurably improved by the experienced types who continue, or return to, instructing once they have moved onto other things.
Cheers
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