Do you place a heading at the top of your file?

I don’t. I think that the Markdown-based note-taking tools I care about rely on the filesystem for organization and filesystem metadata (i.e. filename) whenever possible. So having the title at the top is redundant and is annoying in Obsidian transclusions/embeds.

I’m guessing that the supposed “best practice” of having the title in a heading at the top of Markdown content makes more sense when you’re talking about an isolated Markdown document as a whole; e.g., if you copy-and-paste a Markdown note to send to someone.

Having said that, I would prefer to have the canonical title in the frontmatter and wait for https://forum.obsidian.md/t/use-h1-or-front-matter-title-instead-of-or-in-addition-to-filename-as-display-name/ to be implemented in Obsidian core