This does not directly address your question, but I'll offer it anyway:
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Summary: The DMs I've been with seem to regard the 60-foot rating of a PADI OW certification as meaningless, and most seem to feel a diver should be encouraged to go deeper.
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I have a story that I think will confirm this:
First a bit of background and context:
I had a personal holiday in May this year and I turned it into a diving holiday to get my dives >60 to tick off that aspect of my DM course (I did 11 dives)
I met another customer there who wanted to do a trial dive the next day, being the same day as I was to begin my dives.
The next day I joined her and her instructor just to get experience of how another instructor gives trial dives - it was all nice and calm at 6m and it was a nice learning experience for me. But I digress.
She loved it and wanted to go again. But she was there for the same week as me so the shop owner explained that she might as well do the Open Water Course because repeated trial dives each day, given I was going to dive every day, would work out more expensive. She agreed and signed up for the Open Water Course.
So every day we'd both meet up at the shop, we'd jump in the RIB together, me with my shop-supplied DM for my 1:1 dives and her with her shop-supplied Instructor for her course, we'd go our separate ways (often being dropped at different places) and then we'd reunite back in the RIB later and return to the shop to swap notes.
On day 4 I remember returning with my DM-buddy back to the site where she was being trained for her final Open Water dives and seeing the instructor give the "whoop" signal underwater - she'd completed the final exercise. Cooincidence that we rejoined and so straight away her and I were given the "buddy together" signal and as a four-some (instructor, DM, me and her) we went for a fun dive - no problems so far, max depth was around 14m from memory.
Here's the part of the story that I was getting to:
On day 5, we went out again) this time the whole shop went out: Owner, her instructor, my DM, their other two DMs, and myself. I was briefed that we'd go to a 6m ledge that slowly went down and we (my DM, myself and her) would stop at 18m to let the rest of the group continue >18m, and we'd rejoin later at the RIB. Checking the depth guage, we went to 26m... Of course, there were no issues, and I was on her air gauge like a hawk which they'd seen me doing before anyway so they'd gotten used to my "DM-like" qualities; I was on her like a shadow - to me, it was her dive and the other DM was leading, and I was following shadowing her closely. There was even a moment when she had a blip with buoyancy but a quick grab of her low-pressure inflator hose to release a little air from the pull dump and she was fine again. Finally at 100bar he deployed the DSMB, we did our 5m stop with no issues, again <1m distance from her to cover any buoyancy issues as required, and then the dive ended nicely.
Max depth: 26m, in her logbook went 18m.
The End.