23 years of post-doc with 5 first-authors? That's really all you need to know: that's a terrible publication record for someone looking at tenure-track. A decent target is an average of one first/last author paper a year. Two one year and zero the next isn't a problem, but one every five years certainly is. This doesn't even get into the 'careerism' of picking safe but dependable projects; anyone making reasonable ch…
I don’t know the norm of the author’s specific field but I had the same reaction: His publication record is not even in the ballpark of where it probably should be for tenure. I feel so sad that the scientific industry is set up such that guys like this can plod on two decades or more past the point they should have realized they weren’t on a tenure trajectory. Now he’s 40-something and has to start over in something…
If you want to pursue the academic career, you need to focus on that from the start of your PhD. And you really need to be on some position on a track towards full professor after one or at most two PostDocs.
I'm quite confused by the timeline here, though. A PostDoc is usually something around 2 years, maybe 3. Four PostDocs in 23 years is unusual, and indicates positions that are closer to something like a staff scientists usually done by people with permanent positions.