Some thing that is very important that was missed out on chapter 3 is, well, how do you even get into the group in the first place. MC-kun avoided this issue by being introduced by hinami aoi. If you tried to join a group like that irl, people would be like "who the fuck is this guy? why is he following us?"
I did manage to shove myself into a group table where there were originally 6 people amongst 6 desks, but only because one of them decided to leave early. I could've taken much more upon the opportunity to expand relations but it takes a lot of courage to go beyond what I did, I guess. (All I did was assist them with some problem solving and in return they helped me on something I wasn't paying attention to in the class)
Speaking of using conversation recorders, not only is that uber creepy if someone finds out, it's hard to get one with decent enough quality mic other than perhaps using a phone, and smartphones' downsides is that they are touch screen operated, so you can't operate them reliably without looking at them. I'd also feel like I'd waste too much time memorising a fuckload of topics and probable answers to discuss when you can only expected 1/100th of those to actually be used, and to get reliable answers you'd need to memorise a lot of information, like literally an entire newspaper's worth every week to keep up with what's current.
So no, not a lot of advice is practical in this manga, and that's something an author who probably doesn't have introvertedness (MC-kun is an extravert in this manga, as proven in ch4) or ASD issues (a contributor to the developement of social anxiety) and the alike, will probably not understand fully.