It's not standard because Ren'Py doesn't include it as a bog-standard feature. It requires a bit of hacking to do.
As a possible solution for you, were you aware than renaming the save pages is a built-in Ren'Py feature? Click on the text that says "Page 1" (top right, above the save slots) and it becomes an editable field.
So I have save pages called Annie Best, Annie Oops, Chris Rom, Chris Dom, Sarah, Trish, and one called "Asshole" (where the be-an-ass and blackmail Sarah saves are. Still haven't played those into chapter 3 yet, I need to get into a mood where I want to hate myself after.)