Jackson Pollack, who made splatter painting famous, planned a lot of his paintings with a great deal of effort.

Splatter tests, diagrams, books of sketches, etc.

So does that make him more or less creative? And did that help him become more successful?

I think he understood how shapes and colors can create movement. And even if people didn't realize it, they got excited by paintings with hidden shapes and meanings. He knew how to do that, and executed on it well. Which, in my opinion, makes him much more creative!

The success question coat-tails off that answer since the audience would get excited by his paintings and not by others doing the same thing. Other artist paintings would just look dumb and pointless, while Pollack's would be engaging and cool.

So I think planning made him more creative AND more successful. Even though it looked completely random!