I said sometimes legs are irrelevant depending on how they start. But what film is going to open to 10 billion? None of course. It is an extreme example. If BvS opens at 200m plus domestically, it should be fine. But if it opens at 200m and pulls under 500m somehow, that isn't a good sign moving forward.
The two biggest ideas is money for the film itself and gauging interest in the series and potential sequels. You throw good money after good. It is why TFA had to make 1.5bil to be considered a success. It is why TASM2 getting 700m was a failure. Why we are seeing BvS instead of MoS2. These films cost a lot of money. Over 400m easily when you are all said and done.
I am curious why you think TFA won't have Cameron's films legs when three weeks in, it is still outpacing Avatar and Titanic heavily, and already has a 3x multiplier with the biggest opening ever. But that is for the Star Wars thread.
The thing is, other films ran from TFA. They did not want to compete, and that includes Rogue Nation, Kung Fu Panda and BvS. It is why its legs will not be touched. No other major film wanted to play that game. Will you take that into account when moving TFA and JW or AoU? That is a demonstration of draw power.
Let me work from the bottom. Surely you misunderstand what I mean by how well the latter two films would perform if given the clear skies TFA has been afforded. For I think it's hard to argue that they wouldn't have done better than they did in their original spots. I think that was a basic point. However now you're talking about films running from TFA(not sure bvs did btw) and how that argues something about TFA? Great I suppose it has films running. Now if we could get back to the basic assertion as stated, how much better would said films have done in the james cameron winter spot...Competition plays a factor is the point.
You mention why BvS was made now instead of MOS 2, I'd argue lots of reasons imo. One of which being WB wanted the biggest film of the year and even a 'perfect' sequel to an mcu like performing superman solo wasn't likely going to do that, a jla movie right now probably would. A batman sequel right now likely wouldn't do that...but this, this works. Moreover they get to launch batman post nolan without having to dredge through the basic crap associated with reboots after success..and other reasons.
Personally I believe if the wb brass wants a proper gauge on mos in the 'throwing good money after good' context, they should just toss a hypothetical 2.75 multiplier on it and call it a day. Unless of course they plan on releasing all their dceu(and superman associated) stuff under these same competition circumstances that is.
Next point about TFA's legs(I understand that all relevent box office talk and math is allowed in a box office thread). You yourself can be quoted as saying something about
"Do you know what legs are? It is the percentage of money a film makes after its initial weekend." I'm not that hip to all this so naturally I differ to your opinion as quoted. If this is how the all deciding multiplier theory works then something like avengers has a 3.0(seems right), JW has something like a 3.1(sure ok), GotG has something like a 3.5(ooh very nice)...Avatar has something like 9.7

Now looking at TFA's massive opening(247mill), it total domestic needs to land nowhere south of 2.3billion. Again correct me if I'm wrong.
However if this is infact what legs means I'm afraid this star wars movie has no shot at avatar. That's what I mean by no avatar legs. Which begs the question of who actually cares about this sort of thinking in the midst of totals and big numbers. I'd argue "no one" and you'll see as much in the coverage. Yet it seems to be the crux of all things MOS, not how big it's totals in fact were relative to it's contemporaries. But this mathy deconstruction of legs and such.
The competition was a huge factor. But what other huge film has had competition that hurt it that much? Like any of the to 50 of all time.
Hows about you name a selection of the 'top 50' that faced this particular predicament. That of 150mill of direct comp split between two films vying for very different demos. In week two let alone what was to follow in the subsequent it's very close to a lightning in a bottle situation imo. There in lies the entire point. You probably won't find that many(if any), you sure as hell won't find a single comic book film, a well performing one or otherwise. There's a reason.
I use the extremes to point out the basic logic of a hypothetical. For example when a film(mos) opens strong at number one, then the following week it's at number 3, then the following it's at number 5, then the following it's at number 7, 10, 15...all whilst putting up comparable numbers to something like TWS(which has a very different pattern in this regard), that tells you two things. Either the film is dropping due to inane quality, or big films are opening and taking it's potential audience. The extreme here would be if 30 major good films opened up in the few weeks after MOS and it was sitting at spot 30 in it's third weekend. Is this a sign of it's quality or maybe circumstance? My point being maybe it's time we start looking at this odd thing for what it really is. Not simply at the films expense.
How is it a film opens that big and does 64% drop yet still crawls to near 300 and wins all those blu rays categories? Maybe the answer is staring us in the face. Nothing cut it's legs completely, but things did take just that little amount. Like I said, unless WB plans on doing this every time, they probably moved forward with a hypothetical multiplier.