You can't just take away midnights, they influence the rest of the run.Look at another example, Spiderman 3, it didn't even manage $340m with a similar opening (with better IM) and Memorial Day on its 4th weekend.Now, THG seems to have better WOM and it very well might hit $400m but i repeat, it's not guaranteed.
Looks like i might have to eat my words. With a $66m Friday, $46m without midnights, this might still do $150m for the weekend, or come close at least.Fri: $66mSat: $48mSun: $37m--------------------WKND: $151m
But that's the thing, these things don't shift suddenly by a huge amount, they develop gradually over time.Appeal is the right word and it has a lot to do with it.
If moviemakers / studios would know the exact formula, what it is that makes people go to watch movies, there would only be breakouts. Moviemaking is not an exact science.