Any BB lifetime is going to be a mixture of folks saying 2 rides up to those that have run them for 25 years and still going strong.
For what it’s worth – my BB71 (XT? SLX? whatever it is) push fit was not much different from the external BBs I’ve had on bikes before. First lasted 9 months, replaced and lasted 14 months. I’ve just fitted a Hope stainless one so we’ll see how that does.
None of them have creaked or caused any problems. They are run in all weathers in the NE of Scotland. Including Strathpuffers etc. I’m OK with that as a lifetime – as it’s been said above, dead easy to replace and not that expensive.