How to decrease the height of a "longtable"?

Question

I have the following problem. I have the following code and now I want to achieve that the table is not shown on a new page, but under the section heading, so that the table is shortened vertically a bit. How do I do this?

\documentclass[11pt]{article}
\usepackage{graphicx}
\usepackage{adjustbox}
\usepackage{multirow}
\usepackage{float}
\usepackage{lscape}
\usepackage{rotating}
\usepackage{threeparttable}
\usepackage{multicol}
\usepackage{booktabs}
\begin{document}
\section{A}
\begin{sidewaystable}
    \centering
    \caption{Caption}
    \begin{adjustbox}{width=1\textwidth}
        \begin{threeparttable}
            \begin{tabular}{@{}lcccccccccccccccccccccc@{}}
                    \toprule \toprule 
                                        & & & & & & & &&&&&&&&&&&&&&&
\\\multicolumn{23}{c}{\textbf{Modell 1}}\\
                    \midrule
                    & \multicolumn{3}{c}{$T=4$} & \multicolumn{3}{c}{$T=8$} & \multicolumn{3}{c}{$T=12$} & \multicolumn{3}{c}{$T=16$} & \multicolumn{3}{c}{$T=20$} & \multicolumn{3}{c}{$T=24$} & \multicolumn{3}{c}{$T=28$}  \\
                    \cmidrule(lr){2-4}  \cmidrule(lr){5-7} \cmidrule(lr){8-10} \cmidrule(lr){11-13} \cmidrule(lr){14-16} \cmidrule(lr){17-19}
                    \cmidrule(lr){20-22}
                    & Min & Median & Max & Min & Median & Max & Min & Median & Max & Min & Median & Max & Min & Median & Max & Min & Median & Max & Min & Median & Max \\
                    \midrule
&I&A&A&S&D&F&C&D&W&Q&D&F&C&C&C&C&C&C&C&C&C&\\
                    &&&&&&&&&&&&&&&&&&&&&&\\
                    &&&&&&&&&&&&&&&&&&&&&&\\
                    &&&&&&&&&&&&&&&&&&&&&&\\                \midrule 
                    &&&&&&&&&&&&&&&&&&&&&&\\
                    \multicolumn{23}{c}{\textbf{Model 2}}\\
                    \midrule
                                        & \multicolumn{3}{c}{$T=4$} & \multicolumn{3}{c}{$T=8$} & \multicolumn{3}{c}{$T=12$} & \multicolumn{3}{c}{$T=16$} & \multicolumn{3}{c}{$T=20$} & \multicolumn{3}{c}{$T=24$} & \multicolumn{3}{c}{$T=28$}  \\
                    \cmidrule(lr){2-4}  \cmidrule(lr){5-7} \cmidrule(lr){8-10} \cmidrule(lr){11-13} \cmidrule(lr){14-16} \cmidrule(lr){17-19}
                    \cmidrule(lr){20-22}
                    & Min & Median & Max & Min & Median & Max & Min & Median & Max & Min & Median & Max & Min & Median & Max & Min & Median & Max & Min & Median & Max\\\midrule
                    &I&A&A&S&D&F&C&D&W&Q&D&F&C&C&C&C&C&C&C&C&C&\\
                    &&&&&&&&&&&&&&&&&&&&&&\\
                    &&&&&&&&&&&&&&&&&&&&&&\\
                    &&&&&&&&&&&&&&&&&&&&&&\\                    \bottomrule
                    \bottomrule
            \end{tabular}
                \begin{tablenotes}[para, flushleft]
                \vspace{0.1cm}
                \footnotesize \emph{Note:} 
            \end{tablenotes}
        \end{threeparttable}
    \end{adjustbox}
\end{sidewaystable}
\end{document}

Answer 1

If placing the section inside the sidewaystable environment is an option for you, the following solution should be of interest to you. Note that it does not resort to the adjustbox visual sledgehammer to limit the width of the table to \textwidth. It doesn't double up on \toprule and \bottomrule statements either.

\documentclass[11pt]{article}
\usepackage{rotating}
\usepackage{threeparttable}
\usepackage{booktabs}
\begin{document}
\begin{sidewaystable}
\section{A}
\begin{threeparttable}
\small % 10% linear reduction in font size
\setlength\tabcolsep{0pt}
\caption{Caption}
\begin{tabular}{\textwidth}{@{\extracolsep{\fill}} {21}{c} }
\[1\baselineskip]
\multicolumn{21}{c}{\textbf{Modell 1}}\[1ex]
\toprule
  \multicolumn{3}{c}{$T=4$}  & \multicolumn{3}{c}{$T=8$} 
& \multicolumn{3}{c}{$T=12$} & \multicolumn{3}{c}{$T=16$} 
& \multicolumn{3}{c}{$T=20$} & \multicolumn{3}{c}{$T=24$} 
& \multicolumn{3}{c}{$T=28$}  \
\cmidrule{1-3}   \cmidrule{4-6}   \cmidrule{7-9} 
\cmidrule{10-12} \cmidrule{13-15} \cmidrule{16-18}
\cmidrule{19-21}
  Min & Med & Max & Min & Med & Max & Min & Med & Max 
& Min & Med & Max & Min & Med & Max & Min & Med & Max 
& Min & Med & Max \
\midrule
I&A&A&S&D&F&C&D&W&Q&D&F&C&C&C&C&C&C&C&C&C\
\bottomrule
 \
 \
\multicolumn{21}{c}{\textbf{Model 2}}\[1ex]
\toprule
  \multicolumn{3}{c}{$T=4$}  & \multicolumn{3}{c}{$T=8$} 
& \multicolumn{3}{c}{$T=12$} & \multicolumn{3}{c}{$T=16$} 
& \multicolumn{3}{c}{$T=20$} & \multicolumn{3}{c}{$T=24$} 
& \multicolumn{3}{c}{$T=28$}  \
\cmidrule{1-3}   \cmidrule{4-6}   \cmidrule{7-9} 
\cmidrule{10-12} \cmidrule{13-15} \cmidrule{16-18}
\cmidrule{19-21}
  Min & Med & Max & Min & Med & Max & Min & Med & Max 
& Min & Med & Max & Min & Med & Max & Min & Med & Max 
& Min & Med & Max\
\midrule
I&A&A&S&D&F&C&D&W&Q&D&F&C&C&C&C&C&C&C&C&C\
\bottomrule
\end{tabular*}
\bigskip
\begin{tablenotes}[para, flushleft]
\footnotesize 
\emph{Notes.} \dots
\end{tablenotes}
\end{threeparttable}
\end{sidewaystable}
\end{document}