Depending on the product institutions whether or not to use an acrylic or oil based primer, I use either Muralo universal primer, which is the acrylic or Muralo x200 or the Benjamin Moore Arborcoat linseed oil primers. This particular deck was the Universal.

This is certainly a "best practice" that is probably not typically used. The same is true for painting interior wood doors. Best practice is to at least prime (and preferably paint also) both the lower edge and the upper edge, thus diminishing expansion & contraction with humidity changes.