When to salt, and why I kept getting it wrong
For years I salted everything at the end because someone told me that was the professional thing to do. It is, for some things, and it is exactly wrong for others.
The distinction I eventually landed on is whether salt needs time to move. In a braise or a dough or anything with a large piece of meat, salt has work to do — it needs hours to get past the surface, and adding it at the end just gives you a salty outside and a bland middle.
In a sauce that is going to reduce, or a stock, the opposite: the volume changes underneath you, and a seasoning that was right at the start is a disaster at the end.
So: early for anything that needs penetration, late for anything that is going to lose water. Almost everything I cook falls cleanly into one of those two.