The original HFW recipes for wet brining are far far too salty, and even HFW has changed the salt amounts in later books. I based my recipes on those of "Hilary's mum", somewhere on this forum, and after many attempts made up all my brines with 160 g salt + 80 g sugar per litre of liquid, and immersed the joint for 3.5 days per kg of meat. Liquid can be all water, or half/half water and bitter or cider, sugar can be anything from white to light brown, muscovado or black treacle. This cures the meat perfectly well and the finished product is definitely not too salty. Have no idea whether you need different cures for different breeds of pigs, but I would doubt it, mine were Tamworth and Saddlebacks, nor do I think a pig being in season would make any difference.