[Dave55]

I would say 5 to 7 years for the sealer on the aggregate finish is probably not going to happen.
On a walkway, maybe.
On a driveway with snow removal equipment, possibly deicing agents, I would say every year or two at the max.

 

[Dave55]

The large stone leave voids that the dirt works it's way down into.
That is where the settling is coming from.
When we put a driveway into a garage, #57 or 67 gravel from foundation all the way up to the bottom of the driveway slab.
Even though you can not compact clean stone, a plate compactor run across the gravel does settle it down.
Never had settling issues with the driveway.