Shooting into muscle will do no harm, other than the initial possible pain from the poke. It may absorb more quickly. With Lantus I don't know what sort of effect that would have on the depot (if any).
Bob was on PZI for about ten weeks, and in that time, on all but the first couple of days, he got his shots injected into muscle twice a day, every day (on purpose, not by mistake). Upwards of four units, and he didn't appear to find it painful, but that could be an ECID thing. He never suffered any ill effects, and it apparently still worked since he went OTJ :smile:
Carl