Yeah, I worked for years in a team of 4-6 with no PDM/PLM/whatever. The key was that we all sat in the same room, and our check-out procedure was "Hey, does anyone have xxxx assembly in session?".
Possibly also key was that the chief engineer was part of that team in the same room, and generally you only needed to work on a drawing when he told you to. Because we had quite a few parts which had become common across multiple projects, you didn't change an existing part without careful thought and discussion, so mostly you were only working on new parts unless expressly told to change something.
We also worked on the live folder structure (no WIP copy), although for manufacturing we created PDFs of the drawings and they were stored somewhere else, thus leaving a model or drawing in a half-finished state wasn't likely to affect manufacturing.
Like Antonius said, purging was done infrequently and only after consulting anyone else who'd worked in that folder recently. Back when IT ran a Friday night backup, we also tried to purge on a Monday morning - on a handful of occasions we did need to ask IT to pull some old versions from the backup, but it was very rare.
