Dan, as I'm sure you know, the thickness of lath is about a quarter inch. One hole will tell if you hit lath because you will feel and see from the chips that you will only be hitting wood that's about that thick. You do want to drill on an inside wall and away from potential stud, wire or pipe locations.
My daughter has a 160 year old house that has many of the studs running 90 degrees different from current practice. The wide side of a full dimension 2x4 is parallel to the wall and they are on 24" centers. Actually, this works pretty well with the thicker plaster walls of that time as the total wall thickness and the door casing width are comparable to current practice. When you drill into one of these old white pine boards, your drill knows it. Found some red cedar blocking in there also, between studs. Tried to call the builder about this, but I don't think they had phones 160 years ago and he possibly never bothered to get one. VBG.