The first question I have regards endomorphisms, especially in differential geometry. Everyone who had worked a little in (complex) differential geometry will know that it is very common to write the action of the complex structure $J$ on vector fields without parenthesis, i.e. $JX$ instead of $J(X)$. I suppose that is because of matrix notation, altough I'm not sure. And the same applies to general endomorphisms; it's quite strange to find $L(X)$ in papers. What do you think about? Which one do you prefer? It would be nice to open a little debat with the answers.
The other one also appears in differential geometry, I think it can be extended to any other field though. Suppose that we agree endomorphisms must be typesetted with brackets. Then, consider an endomorphism acting over a Lie bracket. Would you typeset
$$J([X,Y])$$
or
$$J\big([X,Y]\big)$$
(the second uses the comand \big because \left \right has no effect)?
Or consider an endomorphism acting over a horizontal lift. What would you typeset: $J(X^h)$ or $J\left(X^h\right)$ (now the second uses the \left``\rightcommand)?
I mean, does a parenthesis have to cover the content inside always? I mean, all of us agree that
$$(\frac{1}{12}+1)$$
looks horrible but... what happens when the difference is more subtle, as the cases I have mentioned? again it would be nice if we created a little discussion about that.
By the way, I have used article-writingtag because it's the unique that talks about that I think, but feel free to modify it if necessary.