You say you started with a different configuration. Was that a worse configuration or a better one? Do you know more now with 140 dives than you did at the end of your first course? Have you had any failures of the main supply? Have you lost your buddy so often that an OOG situation following separation would have been a real risk? While you were still a new diver were your dives high risk dives needing redundancy? Did having a pony encourage you to go deeper and push things a bit more?
You must have practically dived every weekend since you started. That is not typical. As I said in my first post, beginners need to start easy and build up. A pony is not necessary for the dives beginners ought to be doing. It may be the case that single divers without a regular buddy are paranoid about being out of gas and think that a pony fixes that. That is a difficult place to be.
I started with a 13cu pony and slung that on my left side. I then started slinging it diagonally, as I found it better balanced. I then moved up to a 30cu, but I still sling that diagonally. I dive 2-5 times a week, midweek and weekend, in vis that ranges from 100' (very rare) to I am using a white cane. I can only dive like that as I have all my own gear, rentals are not required.
Usually, I find the top 30' can be very limited vis and quite a few times, one's buddy could be 3' away and you would not know it. A lot of times, we are dropping straight through the soup layer before we see each other again, and conversely, I could be on a safety stop, and have no idea where my buddy is. I am diving in the Pacific NW, off Vancouver Island.
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I have run out of gas once, early on, trying primarily to hover at a safety stop in pea soup vis. I ended up going up and down so many times, inflating, deflating, up, down, oh crap the gas I am breathing feels like it did when my instructor turned off my tank; switch to pony. It was not a gas failure, but a me failure.
My 1st 40 dives I stayed within OW limits, so nothing high risk really, but vis was sometimes a real issue. I started quite easy with my dives, sticking to ones a beginner would be comfortable on, and avoiding high current dives. It was after my 1st 40 dives, I did my AOW, and I carried my pony on that course. My pony did not make me go deeper. Now, I am quite comfortable, swimming along a wall at 100', checking out glass sponges. Also, do not forget, I am also diving in a drysuit, so throw that at a beginner, at the same time. Where I dive, brand new students do their OW in a drysuit.
I was never paranoid about running out of gas, more concerned about a catastrophic equipment failure, that my buddy is not able to help with, for whatever reason. The one time my computer told me I needed to do a deco stop, it got my head going, crap crap crap (ok well maybe a different word was used) while I made my way up. I did not panic, as I had 30cu of gas on my chest to help. Once I hit 40' though, my Shearwater told me I only had to do a 5 min safety stop, whew. I practice switching over to my pony, so when I need too, there is no hesitation. Most of my dive buddies are DMs, Rescue or Instructors, and a large portion dive self reliant. My SAC rate is still higher than most of my buddies, so now when we are deep, my pony allows me to look over at my buddies and wave cya up top, when my gas supply dictates is time for me to head up. The pony gives me knowledge that my 2nd air source is right with me the whole time, and my buddies are confident in my ability to actually be smart about how I come up by myself.