A good ‘rule of thumb’ would be that the article should be no taller than your browser window before the cut, including the site’s header. (Obviously, different people have different size browser windows, but then, they also have different size thumbs). Following that rule, I would think even a single paragraph after the cut should be justified.
ETA: This comes from the print idiom of “before the fold” and “after the fold”.
A good ‘rule of thumb’ would be that the article should be no taller than your browser window before the cut, including the site’s header. (Obviously, different people have different size browser windows, but then, they also have different size thumbs). Following that rule, I would think even a single paragraph after the cut should be justified.
ETA: This comes from the print idiom of “before the fold” and “after the fold”.