There's various degrees of "missing" when you poke for blood. There's the I missed it on the first go, but was able to maneuver things enough that I got it anyway. I don't count this as a miss. There's the I missed it on the first go, and I tried the maneuvering, and I still didn't get it. That counts as missing. Then there's shanking the second one and having to get someone else to come try. That's a total miss. And I'll describe it like that. "I missed totally, and had to get Other Guy to try."
Doing ABGs is different than IVs, since they're deeper and invisible. For doing IVs, there's different challenges: they're thinner walled and thusly like to assplode, the blood flow is passive and so if they're dehydrated or really shocky I can often hit an artery with only mild or moderate difficulty when all the RNs and lab techs around me are doing Hail Mary IVs.
Some days I'm super good, I can hit arteries on people with systolic blood pressures of like 60 or 70. Other days, however, I could have an anxious chick with a blood pressure of I'm sure like two hundred, where I still missed. And I ordinarily can figure out why I missed the first time, and fix it the second time. For example, today, I had that anxious chick: I had absolutely no clue why I'd missed it, and the other arm was worse for feeling pulses, which isn't helpful, so I did my own Hail Mary -- I went brachially, which isn't the ideal way to go since if the artery spasms, there's no collateral circulation to that limb. Which means, in short, if I shank it real bad, her arm might fall off. (Even if I miss, I don't wreck things that bad.)
A second one found me trying to poke arteries that would twist away from my every grasp, to the point where I was afraid, genuinely, of poking into her artery, through her artery, and into my own finger. I tried from two angles and it writhed away, a full half-inch, each time. It was infuriating, because of course, the second time, it just wriggled its way back to the poke mark I'd made the first time. I'm like, whatever God is up there felt like I needed a little smackdown, courtesy the Universe.
So I ask, do you have days where you couldn't hit the broad side of a barn, figuratively speaking? Days you couldn't fix a dead battery no matter how hard you tried? Have you ever thought the universe was deliberately screwing with you?