Why does rendering a pdf from rmarkdown require closing rstudio between renders?

Question

Background

I am trying to make a rmarkdown document that is rendered using render(). The render call has two elements that are parameteri

Answer 1

I found an easy way to do this for multiple .Rmd files was to make a "headers.tex" file with the list of these kableExtra-added \usepackage{} commands. Then in the YAML header of the .Rmd file:

output: 
  pdf_document:
    includes:
      in_header: headers.tex

Here's what I put in the header.tex file -- I'd copied it from one that worked, and it's also the output of kableExtra_latex_packages() stripping off the "header-includes:" line and the dashes.

\usepackage{booktabs}
\usepackage{longtable}
\usepackage{array}
\usepackage{multirow}
\usepackage{wrapfig}
\usepackage{float}
\usepackage{colortbl}
\usepackage{pdflscape}
\usepackage{tabu}
\usepackage{threeparttable}
\usepackage{threeparttablex}
\usepackage[normalem]{ulem}
\usepackage{makecell}
\usepackage{xcolor}