I changed the synch chain after 3 years offroad use because I thought it would need it. It didn't, and it sits in the spares box as a spare. Don't think I will ever use it. The replacement chain has been on for 2 years and other than the initial stretch that came in- I have yet to adjust the concentric to take out any slack. Now both chains were good quality XT grade and not a cheap one.

I do not want to run down cheap chains but I know that mentally- I will go for a grade that I trust and not one that I do not know the quality of.