I also read another study that looked at two similar bridges about a mile or so away from each other: 1 bridge was popular for suicides, and as such had guards put up. You'd think that those people would have just gone to the other bridge, but suicide rates declined in general. I can't find the source at the moment.
[0]: https://www.hsph.harvard.edu/means-matter/means-matter/saves...
No, this is a myth. Clearly there are differences in suicidality. Some people self harm frequently and severely for years before dying. Other people experience "rapid onset despair" and make an attempt.
Recovery is possible for both groups. Most people who attempt suicide do not make another attempt.
There's probably some data in the English NCISH reports here: https://sites.manchester.ac.uk/ncish/
(Also, I'm not trying to police your language. Use whatever words you like. But if you're talking to suicide researchers you may want to avoid "sucessful" or "failed" suicide, and use "died by suicide" or "killed themselves" (both for the UK) or "completed suicide" for the US.)