It's hard to judge. If you can calculate what you've printed per each product, that's the way to tell.
I'd be more apt to have the separate units rather than one. No particular reason though.
And yet, if you're printer is still good and talks to your computer, purchase what you can as this toner is being discontinued.
I found mine on the clearance rack and was shocked at needing to go to that area.
Luckily the clerk at Best Buy thought of it.
I didn't even know where it was in the store.
Good Luck to you.