I wouldn’t worry about it too much, I think most people don’t ever use them… One of my dive buddies who has done a lot of diving in the golf of Mexico on the oil rigs had never operated one before in his life and I had to take him through every step of it. Personally, I never used one or thought I would need one until maybe a few years ago when I was doing months of drift dives in the Philippines off of a speedboat that would find us down the line and get us back on board.. then it seemed like EVERYBODY had one, and for good reason... for a week I held out, thinking Inwas just special,and didn’t need one, then I used somebody’s and realized it made life a heck of a lot easier when everybody is drifting along hanging onto their SMB to stay at a constant depth at a safety stop.
So I went to buy one, only realizing they weren’t cheap - then the Korean guy who let me use his was ready to go back home and gave me his one... which I found out recently can’t be bought in the US (brand name: Argon) and wrote my name phonetically in Korean on it, along with a drawing of a sea turtle, which I thought was really cool of him. I still sometimes bring mine on dives in the gulf when I go spearfishing, but I haven’t really used it very much since coming back from Asia, since we go down and come up within the legs of the oil rigs. And the last couple of times that I’ve been blown off of a rig, I’ve just held up my speargun which has a wooden wing on the front of it to indicate where I was so the boat could get me.. although I’m actually inflating mine now to make sure it has no leaks before I head back to Asia on Monday.