Never, under any circumstances but two, would I sell all rights. I make far, far more money from subsequent rights than from first rights. So will whoever you sell all rights to.
I've had nothing articles written in under half an hour, and that sold first time out for as little as ten bucks, earn several thousand dollars over the next three or four years. There's a reason places want to buy all rights, and the reason is they know how profitable those rights can be.
The circumstances where I have sold all rights are: 1. When a piece has sold and sold and sold and sold until I think most of the profit is gone, and a market then offers me a lot of money for all rights. 2. I had one market offer me so damned much money for all rights to a piece that I couldn't make myself say no. I have no idea whether they made a lot of money later on using the piece, and I don't care. They offered me three times as much as similar pieces usually earn in they lifetime of the piece, so I said yes.
As long as a major motion picture that's a box office smash hit isn't made off the thing, I'm a happy writer.