Argument analysis is the skill nearly every other reasoning skill depends on. Before you can weigh evidence, you have to know which claim it's meant to support; before you can catch a fallacy, you have to see the inferential move it's corrupting; before you can update on new information, you have to have the original argument's structure clearly in view. Taking an argument apart into claim, reasons, and hidden assumptions is the prerequisite for all of it.
What this category really trains is the habit of mapping an argument before judging it. Most people skip the mapping entirely. They read, react to the conclusion, and form an opinion. Once you routinely separate the claim from the reasons from the unspoken assumption, you start noticing what others miss. The assumption taken for granted. The 'often' that quietly became 'always'. The exceptions never considered. The hardest and most valuable version is running that analysis on your own arguments in real time.