As has been brought up several times in this
thread, the big keys to breakdown are
moisture & fineness.
A log, in a tropical rainforest will break down much quicker than it would in the same temperatures in a desert.
That same log, run through a chipper/shredder, would break down probably 10:1 quicker in either environment.
Many people on this forum don't like chipper/shredders (including Paul).
I, personally, look at them as great time savers.
I can break down material in 1/10th the time it would take Mother Nature to do the same thing.
Also, if I am transporting material from off site (or even
on site,) I can transport 10X the amount of material in any given trip.
In the tropics, where things break down quickly, chopping is not so much needed.
In an arid region, I think that chipping/shredding is almost a necessity.