I have a specific way of displaying Chapter title headings, by placing the chapter title in between two rules. I use titlesec to achieve this. The issue is, the stretch that LaTeX does over each chapter title page may be different and so the text within the rules is not always exactly centred.
MWE below. Chapter 1 title text is centred, almost perfectly, between the rules (as the \titleformat{\chapter} code was written by looking at this first chapter title). However, for Chapter 2, because the text afterwards is now different, the title text is no longer centred. Please disregard the fonts and sizing. It's the best I could manage to show my issue without just copying my entire actual code. I am sure there are many ways to overcome this. Would an environment do it? But could this be incorporated into titlesec?
\documentclass[10pt,a4paper,twoside]{book}
\newcommand\YUGE{\fontsize{38}{45}\selectfont} % creates an even bigger 'YUGE' font size, at 38pt
\usepackage{titlesec}
\titleformat{\chapter}[display]{\sf\YUGE}{Chapter \thechapter}{-5mm}{\rule{4.5in}{1pt}\vspace{-3mm}\\\rm\huge}[\vspace{-9mm}\rule{4.5in}{1pt}]
\usepackage{lipsum}
\usepackage{parskip}
\setlength{\parskip}{1\baselineskip plus2pt minus2pt}
\begin{document}
\chapter{Example Chapter Title}
\lipsum[1-2]
\chapter{Example Chapter Title}
\lipsum
\end{document}
\parskip
value to see how it works.