Here is how most people read a 401(k) statement.
Open. Find the big number. Feel either mildly pleased or mildly ill. Close.
Total elapsed time: four seconds.
And honestly, that is not the worst approach in the world, because most of what happens quarter to quarter is noise. But it means the average person has never noticed the three or four things on that document that actually determine how their retirement turns out.
The statement is not designed to hide them. It is just designed by people who assumed you already knew what you were looking at, which is a charming assumption that has never once been true.
So let's go through it section by section. Fifteen minutes, once, and you will never look at one the same way again.