Totally agree...
I had an interesting conversation with a fellow on my last trip who was tech-rigged (long hose, bungeed alternate) carrying a 6 cuft pony, who said he wanted to be prepared for an OOG event at 100 ft while diving solo. I asked him whether he thought his 6 cuft were enough gas, and he proudly explained he'd tried using it for an ascent from 100 ft and had made it just fine, including a 3-min safety stop. We worked through the numbers, and he'd come up at 60 ft/min, and was breathing his normal SAC rate. And, of course, he'd used the entire 6 cuft to do his ascent.....not allowing for any accelerated breathing, or time-spent-on-bottom before ascending, or any other issues. He kept looking at his little pony, kind of unhappy after the concept of cascades was pointed out. Then I showed him how his long-hose was fouled -- by having put his necklace on last -- if he tried to donate it. His reaction? "I'm diving solo, I don't need to donate it." Oh, well.