Making a movie is the ultimate team endeavor. Even the best in the business have to rely on more than just their individual wits and expertise to get something worthwhile up on the screen. Because although it might only takes one person to ruin a movie, it takes a collective effort to make it great.
That's why it's no guarantee that a film created by someone with a sparkling track record will be a success. It's also why so many directors like to work with the same actors over and over. They know, no matter what else happens, at least they can count on that familiarity.
Of course, actors appreciate that closeness, too, because they know exactly what the director wants from them. It's just more comfortable for everyone involved.
Those types of relationships often produce excellent results, partly because their mutual appreciation and respect allows them to take risks without all the nauseating "what ifs" clouding their judgment, and partly because you don't choose to work together repeatedly unless you like how everything turned out.
These actor/director partnerships brought out the absolute best in each other.