Other than looking neat, I never really saw much steaming action even when I started with 1/2 can of hot water. I do cook the breasts on a rack without a can, which works good.
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And not just for laughs.... I'll do this presentation on occasion, again without a can.
BUT, there is some science involved. I freeze the lemons, so they keep the breast cool for 20 or 30 minutes so the dark meat can get a head start. A few times I have made slits in the pulp and put pieces of garlic, or garlic butter in them before freezing. This self bastes the breasts while cooking.
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