Everything I've found online says to put the high point in the middle of a long gutter, but it doesn't say what the seam should look like.
What goes in the middle of a gutter run with the high point in the center? Do you cap both ends and leave a small gap between the right and left? Is there a special pre-made joint?
For crowning the middle on a long gutter run, you typically use a slip joint or expansion connector in the center to allow for movement while keeping the high point. Check your local hardware store for pre-made gutter unions that fit the seam style you're using. #diy