Once you know the precedence table, this:
$x >= $x_min and $x <= $x_max and $y >= $y_min and &y <= &y_max
...looks the same as this...
($x >= $x_min and $x <= $x_max) and ($y >= $y_min and &y <= &y_max)
...and is no easier to read. In fact I would go so far as to say the last example is slightly harder to read because of the extra parentheses.
In short, I think that no reader benefits from "documentary" parenthesis if they know the precedence table - and a programmer that doesn't should be told to spend the few hours it takes to learn it - rather than the rest of us constantly worrying about them when we code.