I heard that only reading the abstracts of articles and then using them to make claims is bad. However, I often find that much of the information I read useless for me. For example, often the introduction gives me no useful information because I'm already introduced to the subject or the abstract gives no useful information because I already know the article is what I'm looking for. Much of the information in the methods section also seems unimportant to me as I want to learn about how reliable a study is (such as by looking at sample size of if it's a randomized controlled trial, correlational study, etc), and I'm unconcerned about the specifics of the experiment.
So, what parts of scientific articles should be skipped and when?