Not sure why you'd respond about Spider-Man in the Wonder Woman thread
Anyway, big movies always have smaller increases on their first Tuesdays than later on in their release. Anything above 20% is pretty good.
Look at other movies in the last 2 years and you'll see my point. First Tuesday increase is pretty much always the lowest if there's no unusual factors affecting it. Ant-Man was released in July as well and had a 22.6% increase on the first Tuesday and it had great legs. 24% is by no means anything to be alarmed by.
Whether it's mid summer with schools out or not, first Tuesday increases are usually lower. And that's a fact, not an opinion.