I think you overestimate him. He's not methodical, he just sort of passive. He goes where the wind flows and hopefully it flows towards sex. He doesn't manipulate them into consent - the very nature of this world he's in conviniently does it for him, so he just lets it happen. The guy actively avoids thinking about consequences and just goes with his gut all the time. He's all about escapism.
Alternatively, he sort of has several layers to his thinking, where the surface one is passive in a go with the flow sort of way and the other, deeper one is more, as u called it, methodical. It also dictates some of his choices that seem random at a glance but actually very significant and deliberate. Like giving Maya a green scarf as a gift.
Isn't Molly scene in the same vein as Yumi's one, just more severe?
He's specifically avoiding the easy way, which also happens to be the more dangerous way as far as his overall plan. There have been several opportunities for him to get an easy target off a girl who wasn't completely incapable of stopping him and he didn't take any of those. I would say that this seems like planning around his overall plan to get with all of them eventually, not necessarily all at once considering the lack of plans for a harem ending. He definitely manipulates at least a few cases where it led to something, in fact,
the Miku thing in her dorm might have gone there had what happened outside the room not happened and Makoto hadn't shown up and that was clearly manipulation, she wasn't even close to ready to go even as far as she did. If the very nature of the world did it for him, they would already be actively doing things. Sure, there's a little force pushing them toward him, but not enough to make them do what he wants without question. He is not blameless in several cases, especially the one in the spoiler.
I think that go with the flow thing is just his outward appearance, he isn't actually going with the flow, just seeming like it to be less conspicuous.
I had thought the Molly scene was another Yumi kiss incident at first, but on further inspection, I don't think it is. I distinctly do not remember him mentioning, even in his thoughts, that he was not in control, which he did with the kiss. When he actually loses control, it seems to surprise him on an internal level that didn't seem to be present in the Molly scene.
No, I doubt that he is methodical aiming for having sex. From the above Yuki event, where suddenly Yumi meets her mother and after some fight between the two runs away and the MC follows her. His thoughts:
So no. There is no planning involved.
I'm not convinced. He's done this before only to go and do more awful things to another girl. I don't count the Yumi kiss he mentions in the quoted text because he was quite obviously confused, even frightened that it happened. However, there have been several incidents now with none of those feelings and one in particular was quite obviously instigated by him.
He's lying to Karin while going out with her sister behind her back, he manipulated Miku to start stripping, which I can only see as having been stopped where it was because of the noise outside triggering one of her episodes and Makoto entering the room, he used Molly for oral when she was passed out, he took advantage of a clearly intoxicated Makoto to take her first time. I am already dreading what comes next since we haven't reached peak Denpa yet, which is good for a Denpa game, that's exactly how I should be feeling as that means the game is doing its job.