In my opinion, I think an inexperienced ee is in safer hands with an experienced er usually. I wouldn't consider that a rule, but a safer assumption if you had to make one. The intent and maturity of the er matters. I also think that a less experienced er can be safe to explore with - again depending on their maturity level. When I'm talking about maturity I'm not talking about age. I'm thinking self awareness, social calibration, self-control, and a skill for recognizing nonverbal communication. In my M/s world I'm fond of repeating the quote that "Every Master was once a disaster." I don't know who the original origin of the quote is, but it's very true.
I was a wrecking ball when I started with DD. With experience I learned a great deal. Experience is generally safer, but without an opportunity to gain that experience, an er can't become wiser.