Thank you for the report. I can see where you are coming from.

I'll see whether something like citereset=subsection+ which would reset at \part, \chapter (if available), \section and \subsection is possible. I would not want to change the current behaviour of citereset because the behaviour is documented and established.

A first implementation idea is at dev...moewew:persectplus. Testing and comments would be appreciated. You will need Biber 2.12 dev (https://sourceforge.net/projects/biblatex-biber/files/biblatex-biber/development/binaries/) to test this.

edit If you don't want to get a new biblatex and Biber set-up just for testing, you can use the drop-in replacement for biblatex.sty v3.11 from https://gist.github.com/moewew/d12e0fe557fadd165c3132b501252fb4. Please use it only for testing in a separate folder, it is not for production use.

I appreciate the drop-in, thanks. It tests nicely on my end!

My comment would be that subsubsection, paragraph and subparagraph could be included in this function as well, for completeness.

Also somewhat related: some writing styles reset ibid.'s at every paragraph, but since \par is not a sectioning command i assume that would be a different problem?

Thanks for testing.

Mhhh, theoretically it should be easy to include \subsubsection, \paragraph and \subparagraph (at least for article.cls etc.). But I'm wondering whether people really need that. Maybe PL had a reason not to include those sectional headings. Lastly, and that ties in nicely with your last point, paragraph may lead people to think that the reset would happen per paragraph (\par/empty line paragraph that is), which it won't.

I'd love to have something like citereset=par, but I'm not aware of a safe method to execute code at the beginning of each paragraph. See also #715

In biblatex 3.12 you can use citereset=subsection+ to reset the trackers at all sectioning levels of subsection or higher.

\documentclass{article}
\usepackage[style=authoryear-icomp,citereset=subsection+]{biblatex}
\addbibresource{biblatex-examples.bib}
\begin{document}
\section{section 1}
\subsection{subsection 1.1}
\parencite{knuth:ct:a}
\subsection{subsection 1.2}
\parencite{knuth:ct:a}
\section{section 2}
\parencite{knuth:ct:a} (should be reset)
\end{document}

biblatex 3.12 has been released and is available in TeX live 2018 and MikTeX as of this morning (UTC).