Edited my original post to add images.

I have not used 3DGS in a while, could a recent change to WED be causing this?
It has never been easy to avoid these issues but I do not remember it being this bad.

How to quickly reproduce the problem:

Create a cross pattern with 5 blocks,
Raise the outside edges of two blocks, lower the outside edgers of the other two blocks leaving the middle block flat (imagine two ramps going down and two ramps going up to a flat plane),
Now fill in the cross pattern so you have 3 rows of 3 blocks.
With snap ON (32) I can not avoid having seams (very tiny gaps).