The following MWE illustrates the problem
\documentclass{scrartcl}
\usepackage{booktabs,tabu,blindtext}
\begin{document}
\begin{tabu} spread \linewidth {X}
test\\\midrule
Nunc quis urna dictum turpis accumsan semper.\\\midrule
\blindtext{}\\\midrule
\blindtext{}\newline{}test\\\midrule
asdg\\\midrule
\end{tabu}
\end{document}
The line space is not the same, if there is a linebreak in a row. I would like to have the same line space in the entire table.
\strut
to the second line marked line fixes the problem. You should probably add a\strut
to the first case as well. I am guessing that the reason it is not absolutely necessary for the first case is that the line does not span the entire width of the text. If you add enough text before it so that it is not just a short line, then you will see the effect.