What if the tree was cut up and the pieces sat around for 4-6 years then split?  Is it necessary to still wait 6 weeks after splitting the aged logs? 

The problem is surface area for the water to evaporate from.  I have some such logs sitting on one of racks.  They are still nearly as heavy as the day I put them there.  Seasoning the wood for the 6 weeks is still a good idea.

You could always split them then see how they perform.  If they perform well, then use them!

In some humid climates, the seasoning time is obviously longer.  If I were to buy a cut cord, I'd want it split 3 months or more before I'd buy it.

All this depends on how it's stored as well.  I've seen people store stacked firewood on the ground, which allows the wood to wick up moisture from rain and snow.  Cordwood should be racked and stored on pallets, with air circulation underneath.  

Jennifer, some log sections will rot in 4 to 6 years.  Depends on how it's been stored.

So true, Eric.  We would love to have wood that has cured for that long as well, we are unable to find anyone that does that in our area.  Hence the reason for stating the 6 weeks is the bare mininum!

Thanks for the comments thus far.