Beamer default overlay: show subitem at the same time as the item

Question

I would like to use the overlay system in beamer, yet only at the first level of a itemize list. In other words, I want A then B, yet A.1 and A.2 to show up at same time than A.

The post: Beamer: show subitem at the same time as the item shows how to do this manually. Is there a way I cam set this as the default behaviour with \beamerdefaultoverlayspecification{<+->}?

Answer 1

I was also trying to figure out how to do this. I don't have a full solution, but this at least is an improvement for large outlines.

Add [<.->] to each sublist. Then all subitems will appear with the item.

\documentclass{beamer}
\begin{document}
\begin{frame}
\begin{itemize}[<+->]
\item A
  \begin{itemize}[<.->]
  \item a1
  \item a2
  \end{itemize}
\item B
  \begin{itemize}[<.->]
  \item b1
  \item b2
  \end{itemize}
\item C
  \begin{itemize}[<.->]
  \item c1
  \item c2
  \end{itemize}
\end{itemize}
\end{frame}
\end{document}