Apparently for interior walls, the lathe is usually attached to a stud. Exterior walls are different and it can be just stuck to masonry (but I've seen the guts of my addition, and I know there are studs in at least some of the walls...followed by what looks to be pine or oak flooring-like-material, then lathe and plaster).

Some googling has recommended getting a REALLY strong magnet, like from a hard drive, and tying it to a string. When dangled near a wall, it will find the nails in the studs and thus, the studs.

We'll see.

(Note to self - google before asking random questions).

Thanks Tulip!