I feel like initially, it became more and more important for the leads to be placed correctly. Eventually, you get to that point where you recognize the patterns of lead misplacement, especially the VERY common ones like lead V1 and V2 being placed 1 intercostal space too high, lead V3 being misplaced on females due to scary boobs (in combination of lead V1 and V2 being too high because of boobs... I tend to notice "weird" R-wave progression on female patients most, lol), or the limb leads being swapped, which have easy to recognize patterns (short right arm (RA) and left arm (LA) lead vs left posterior fascicular block (LPFB) not being something you can tell with a cold read, though a LPFB being rare by itself so RA and LA reversal being more likely if you see "LPFB" by itself). I dunno. I stopped caring. Same with "limb leads go on limbs". Like it causes slight rightward axis shift, but I personally don't consider it significant enough to change how I interpret the 12-lead; I'm totally okay with Mason-Likar/torso placement. If people a really going to be anal about it though, they could document it on their PCR and/or some monitors allow you to add a comment/note "torso placement for monitoring", "torso placement to minimize artifacts", etc.As long as the leads describe Einthovens Triangle(plus the ground), and aren’t impeded by implanted devices, hair, etc, any placement will be suitable for rate, rhythm, and STEMI interpretation. If you want to start getting into the nuance electrocardiology world, then specific placement becomes imperative, but for the EMS world, its of less importance. I try to remain consistent. If the arm leads go on the chest, the leg leads go on the abdomen and so on. Ive never tried to acquire an ekg with the leads all cattywampus all over the body, but I suspect it might be curious to look at. If you’re a basic reading this, find out what your medic wants and do it that way. You wont score any points arguing with your medic on technique, right wrong or indifferent.
The people that will consider this heresy are usually the same people that will tell you not to take a blood sugar from a venous sample because of the contextually irrelevant difference in the reading you will get between a capillary sample and a venous sample. They aren’t *wrong*, but there are far more important hills to choose to die on.