I became a dive professional with a mainstream agency before I found Scubaboard. I was then dry for 18 months as I learned more about alternate configurations, more about tech diving, other agencies, cave diving, CCR, and everything else scuba related that is beyond warm water recreational diving.
Once I learned about the long hose and primary donate, it didn't quite make sense to me at first. Why would you want to wrap it around your body? What if I don't carry a canister light? Once I saw it in real life and thought about an out of air situation and what I would have done as a novice diver with 10s instead of 100s of dives, I decided to use that for my setup. I thought it made sense to grab/donate a reg that you and your buddy absolutely know the location of without having to look.
Fast forward to the first diving trip I took with my long hose configuration. Dive boat...insta-buddy...led by instructor guide. My buddy was too far away from me. The other dive pair in my group was between me and my buddy. An o-ring on my SPG went and it started free-flowing. I thought this was going to drain my tank fast so I looked first for the dive guide, but she was facing the other way and farther away in front. I moved in to the closest person in the other dive pair, but I couldn't find her alternate. It was tucked behind her in the pocket (rental gear). By then her buddy had seen something going on and swam closer; I saw her alternate in the triangle and grabbed hers. Then the instructor/guide came over and switched me onto her alternate. I remained calm throughout this process and thought about my actions.
My biggest takeaways from this incident were: 1. I didn't realize that the HP hose has a tiny hole and will last longer in that situation than an IP hose to the second stage. 2. I needed to be better about situational awareness and staying close to my buddy, even if they are being annoying and slow and aren't looking at the things I want to. 3. Someone's octo may not be in the triangle, but I always know where to find the primary.
As a result of this, I trained more; I practiced more; I always brief my dive group on my setup; I always stay close to my buddy; I prefer to dive redundant. Since then, with more experience and hundreds of more dives, when I've had to share my primary, I've always been able to anticipate the experience and have it right in front of the donee when they need it.
I also value diving in trim and being able to maintain that trim in an air-sharing situation (even in recreational diving). What I know about decompression theory also makes me want to be ascending in horizontal trim rather than a vertical position. That's going to be difficult for most divers with the typical recreational setup with a 40" octo.
I just share my experience. Your mileage may vary and your training and perspective may be different.