mm wrote:
A neighbor has a stockade fence, with pickets about 3 inches wide.

It's been in 5 or 7 years and it's easily possible to see between the
pickets into his yard. It wast very difficult to see anything when
the fence was new.

Does that mean the fence was built with pickets that hadn't been aged
enough before construction???? Have the boards shrunk more than they
should have??

A friend likes the fence otherwise and wants to hire the same company,
but I think she may get an inferior job, if this fence is inferior.

Pressure treated lumber is soaked in the anti-rot chemicals and expands.
When erected, it dries and shrinks.

One solution is to buy the pickets needed and stack them in a dry place -
with plenty of air circulation - for a month or two before installing.

The gaps are not the fault of the installers. It's what wood does. Some
wood.