Is it actually possible to read 4 posts in 4 different sections within less than 2 minutes? It looks like he just decided that he wants to give merits and clicked the last posts of them and sent merits.
Even if you read the posts, it should normally take 2-5 minutes considering the post was merit-worthy.
There is no rule that says you have to send merits immediately reading a post. In fact, someone who plans of meriting a few posts and perhaps has a limited number of merits to spend, would likely open a bunch of posts in tabs and/or bookmark them, decide which ones to merit and how much, put the numbers into boxes, and hit "Send" within seconds. I've done this literally thousands of times.
Thanks.