Because you still want to bleach your whites. Sheets, towels, t-shirts from the gym... bleach goes all over that stuff, and it smells great! (And yeah, anyone who doesn't have white towels is doing it wrong. Eww, can you imagine all the filthy on a towel that hasn't been bleached?!)

Separate cloths by colour, and by type (glad you're doing half of that already!)... you wouldn't wash jeans with dress shirts... let the machine's auto-sense take care of the quantity / duration issues.

> Eww, can you imagine all the filthy on a towel that hasn't been bleached?!

I assume you also bleach your underwear and socks? T-shirts? Gloves? Pants? Dish towels? Sheets?

I separate synthetics because the dryer damages them and I don't want to do it when they're a wet mess.

I separate my clothes. I separate some because I’m going to hang them and it’s easier to separate while dry. I separate others because they have wildly different levels of durability and ruggedness. I don’t want my jeans abraiding my button ups.