I think it is important to consider the niche when you are looking at directly linking as opposed to a review or squeeze page, or a website or blog. There may be certain niches where your readers are so desperate, that they literally need an article to confirm their deepest fears and then a simple affiliate link to lead them to the solution (e.g. get your ex back - direct linking). Whereas other niches will require you to build a level of trust with your readers before they purchase through your affiliate link (e.g. premature ejaculation/penis enlargement - squeeze page) and then there are the niches where people want to absorb as much information as possible and will only ever purchase from you if they view you as an authority (e.g. weight loss/build muscle - squeeze page + lots of content on a website/blog). The niches I have mentioned are merely an example. The only real way to discover what is best for you is for you to test, test and then test again.