I don't think the scenes are repetitive at all, but repetition is a good thing when it comes to porn.
You have to understand that the girls are getting fucked by big cocks in the ass.
So imagine the scenes were going to have the exact same format every time (which they don't), but imagine they were going to.
You can have a format, just to name any, where the girl is standing looking at the camera and the guys are behind her ready to fuck her.

While she looks at the camera the first guy is already behind her, and all of the sudden his cock is already up her ass.

She can feel his cock so she bends over a bit to sustain the penetration better, then the other guys approach and now she is giving handjobs, and tasting cock in her mouth while getting fucked in the ass at the same time standing with her legs trembling for the sudden penetration.

The guys basically take turns in her ass, and then they put her in the coach to fuck her doggy style, all of them, they all fuck her, and she keeps getting penetrated in the mouth as well.

Eventually guys decide to start going two at the time on her ass, so now she is taking two cocks in her ass while sucking cock too, all the guys fuck her that way.

But now they want to carry her in the air, so now she is in the air with her legs floating getting penetrated by different guys while she is carried, they take turns on her ass, and she continues to get fucked even on the air.

After that they put her against the wall, and they go Chu Chu on her ass, pounding that ass one after another while she holds on to the wall with her hands to withstand the pounding.

After they do that to her the put her flat face down prone pone so they can start mounting her with their big cocks going balls deep on her ass. You get to see her beautiful legs extended while she receives the penetration, and at that moment her reality is sucking cock while another man is on top of her enjoying the insides on her intestines with his cock.

At this point she has been penetrated in the ass for a long time, one cock after another have been inside her rectum, and it's time to cum on her, so they put her on the couch again and one by one the guys start using her ass to get to the point of cumming.

One guy comes in her ass, another one decides to come in her pussy even though it was ignored during the whole fuck, and all the other guys cum all over her face making sure her whole face has cum.

So now she is on her knees dripping cum from her pussy, dripping cum from her ass, and with semen covering her face, right after have been getting deep anal penetration for an hour or so that she can still feel the phantom sensation of the cocks stretching her anus.

But before she moves out from that position all the guys stand around her and piss on her face directly aiming to wash off all the semen that was covering her, and now covered in piss and semen she says good bye to the camera.

That's a video.
Now the beauty in repetition is that the viewer already knows what is going to happen to the girl, so every time you see a girl coming out from that door the viewer is excited to see it done to her, they want her to experience all of that, and it is very exciting because you already know she is about to get pounded that way.
And this is why repetition works because it has three phases:
Phase 1: It gives you the excitement of knowing what's going to happen to the girl.
Phase 2: It gives you the excitement of seeing it happening to the girl.
Phase 3: It gives you the excitement of seeing that happened to that girl.
But that's not the end of it. In 15 days, that exact same girl will come back to have it done to her again.
Phase 4: It gives you the excitement that now it is not just the viewer who knows what's going to happen to the girl, the girl also knows what's going to happen to her because she lived it already.
So now the viewer and the girl have something in common which is knowing what's going to happen to her. Her asshole already recovered from the previous gangbang, but now is about to take another round of penetrations, and she knows it, and the viewer knows it, and she is there knowing that's going to happen to her, and she has willingly put herself in that position so the viewer can enjoy seeing how they do that to her.
It's a beautiful thing because every 15 days she knows it's time to get fucked in the ass and pissed on the face, and she knows exactly what's going to happen to her, so as soon as she feels that first cock in her ass she knows she is there for guys to have another go at her ass and ride it like there is no tomorrow.
It's literally impossible to get tire of this, instead you want to see it more and more, over and over again, you are literally paying to make sure these hotties go through that whole ordeal again and again because you enjoy seeing it happening to them, and the more the hotties get fucked in the ass and pissed on the face, the happier you are.