https://support.posit.co/hc/en-us/articles/204463668-Code-Snippets-in-the-RStudio-IDE

Ever get sick of looking up the same values over-and-over when setting up a new markdown file? Or writing the same function type to do a specific type of processing in different projects? Usually I look back in some of my old code and copy out the relevant bits that I need and modify them in place. But while reading Hadley’s “Mastering Shiny” book, I came across this.

You’ll likely quickly get sick of typing that code in, so RStudio provides a couple of shortcuts: If you already have your future app.R open, type shinyapp then press Shift + Tab to insert the Shiny app snippet.

And in the footnote for that section, a link to this page - https://support.posit.co/hc/en-us/articles/204463668-Code-Snippets-in-the-RStudio-IDE.

This is a game changer.