Well, I think we're looking at this a little obliquely.
The second week drop off rate has been a struggle for Hollywood for a few years now, whether the films have good reviews or not. The majority of publicity and advertising is loaded solely at that opening week(end) and then basically gets dropped. This isn't just a DC issue, not at all.
Look at 2014 - Amazing Spiderman saw a 61% drop off, Godzilla saw a 67% drop off and X-Men Days of Future Past saw a 64% drop off. In 2013, Iron Man 3 saw a 58% drop off. In 2015, Age of Ultron saw a 59% drop off.
Heck, even Civil War dropped 59%.
Admittedly, where a film posts on that first week(end) has a big impact on how much that drop off looks. Civil War hit massive, so its second week is still huge ($90+).
So, to see a 67% drop off, though sounding huge, it is more dependant on what the third and fourth weeks look like. Will it drop a further 60-70% or not? BvS, with its 69% drop off, was hit hard, but it then had another 57% drop off in week three and, by week, four, barely scraped above $10m.
With so much content available, not only at the cinema, but at home too, barring the uber-fans, repeat theatrical viewings are few and far between, if not wholly excluded from most people's "social-equation" full stop. To have true "legs", like that of Avatar, Titanic, or The Force Awakens, you have to create a product that is beyond the fans, outside of that niche model of "curiosity". Otherwise you bank on your first weekend hoping to refill your coffers.
Suicide Squad certainly fits that mould of being a "niche" product, and its first week(end) performance was very likely carried by the "uber-fan" and standard cinema-going "curiosity", thanks to a strong ad campaign. But does it have repeat value? The film comes with generally high audience ratings, which one would think would drive people back for repeat viewings. But with (frankly) daft ticket prices, the real repeat-value of the film may not be seen until it hits VOD/Blu etc (something like Guardians of the Galaxy did $128m in US DVD/Blu Ray sales, alone).
But a $175m price tag and $150m marketing campaign, films like these need to burst out of the gate HUGE so they can at least finish the race, rather tripping at a second or third fence because they ran out of energy to carry them past the "break even" post. SS will struggle because, as an unproven property this small, it should not be playing in the £200m sandpit. Marvel took a gamble on Guardians of the Galaxy and it paid off. Now all of their films will have the £175m+ budget and will continue to do so. DC wants to play in that sandbox, so created an OTT spectacle of a film with an inordinate budget (for its property and exposure) and may suffer the consequences. A more Deadpool approach would have perhaps suited the film and trimmed some of its excesses.
The film makers/production company also somewhat shot themselves in the foot by creating a story that doesn't fit the international box office model - you want money, you want China. You may only get 25% back, but in the case of Transformers or especially Pacific Rim, you want that extra £100-$300m that China will bring you. No film fan or critic wants to see films that are "tailor made" for countries, yet any production company would be daft to not want it on their portfolio - goddesses and demons for SS could nail the coffin shut for DC on this venture, like it was for Ghostbusters (which was doomed from the start - China was NEVER going to allow it to be released with its obvious content issues).
Hugo - disliked the film greatly, but day after day had edged closer to loathing it