This is basically a follow-up to the comments on this answer which I couldn't find to be settled anywhere. I learned that you can write ordinary bracket simply using
but that you can also use
f \left( x \right)
where the latter automatically adopts the brackets' size, but creates a space between the function and the bracket.
My question is: when is one supposed to use which version. Is the second version only used when the "content" of the bracket is not an argument of some function? What if it is a long and complex argument, where I want the brackets to be increasing in size? Would I then use
f \! \left( long expression \right)
or is there some other solution for this?
Edit: While I found some solutions regarding the space adjustment, I was still wondering when to use which approach, i.e. whether there are some "best practice rules" for this.