What in 3D works/Hentai/Porn ISN'T "predictable"? I mean, let's be honest: what haven't you seen before? You'll usually find the audience in two camps: (1) the monoamorous and fringe harem camp, where the sexual exploits are exclusive to just the main male character and the main female character or the main male character's harem, or (2) the polyamorous camp, where it's more like modern pornography and anything goes, i.e. an "Eyes Wide Shut"-like Bacchanalia of debaucherous sexual exploits limited to no one sexual partner, regardless of whether it's the main male character or the main female character (but typically, the main female character.) Those who claim it's boring are probably in camp 2, while those who are rebuffing their comments are probably in camp 1. I personally couldn't care less for Martha and Sophia, and would personally like to see the sex remain just between Daniel and Lana. Do I think it will remain that way? No. I assume Daval is keeping his options open, and teases prospects like Daniel and Sophia, or Daniel and Sophia and Martha, or Daniel and Sharon and Friend, etc. I think, and this is just my opinion, that once he milks the Mother-Son incest angle, he'll eventually attempt to appeal to a different crowd. Because it's clear, to me at least, that Daval is in camp 2, but because of Daniel and Lana's popularity, caters to camp 1. I don't think Madness Together is necessarily better because there are different characters. Even though I like Madness, it's a bit of a mess, because Daval is reeling back from the Uncle Peter controversy, so in my assumption, he's finding ways to keep the characters, for lack of a better term, "occupied." You rarely find artists who'll find ways to end their stories on a good note (e.g. the late Redoxa) and start anew.
Only time will tell. I just know (assume, really) that one of the two camps I mentioned before will not be happy by the end.