For a while we’ve been baffled about how very fallible Garnet’s future vision has been presented in some cases and how very effective it’s been in others—see Future Boy Zoltron for an example of her displaying a masterful command over her future vision, for instance.
Ever since Future Vision we’ve more or less had it right: Garnet’s future vision is based on probability, and her understanding of the current conditions is important for her getting the probabilities right. What we’ve been missing has been something to bridge the gap, explaining how Garnet can know all about Frowney in Future Boy Zoltron but be befuddled by Steven’s actions at every turn.
Pool Hopping finally came in to explain, and then dramatically show, the last missing piece. When Garnet is sitting there in the rain, holding the kittens, she still sees all the possible futures that could befall the cats—it’s picking a likely future she can’t do. It’s only after the cats are safe and dry, and Garnet has re-evaluated what kind of behavior she can expect from Steven, that she feels confident again.
It’s as simple as can be, for the most part: Garnet has come to expect Steven to act a certain way, and it’s only after seeing Steven take charge in a small yet touching scenario that she realizes that his desire to take proactive steps is his new likely behavior rather than an improbable occurrence.
Her previous big-ticket failures, at least the most recent ones, are explained as her expecting Steven to continue to act like he did earlier in the series. Whether Garnet’s future vision will prove more accurate in the future of the show remains to be seen, but at least we know why Garnet has been missing some important stuff lately.