2006 Mazda 5 : 2.3L motor with about 170k miles on odometer and wondering if a timing chain replacement should be done.
Finding contrasting information regarding if it should be changed or not.
No mention I can find in the user guide.
I have no current problems or audible rattles, timing issues, etc.

Found this video stating that the hydraulic tensioners fail along with a stretched chain causing chain slap against the valve cover.

 

Unless its noisy or stretched ( dtc), there is no reason to replace it.