I’ve Printed LOTS of PLA living hinges and even springs. They do work just fine for the limited to moderate cycles they last. I’ve printed 100’s of toy catapults and other small toys in PLA and then handed them out to 8 and 9 year old children. They held up amazingly well under that abuse.
At some point the toys would fail, they were 8 and 9 year olds after all, but it could take a month or more in the hands of children. I was pretty shocked. I did have a paper wad cannon that had a spring that was printed all in one inside the barrel. The first few had issues with the compression spring breaking when over compressed by the kids. But a bit of a redesign of the spring by making it beefier, it not only lasted nearly the whole school year but the kids got more range. Much to the other teachers and parents disappointment.