That's right! I do not sort my laundry. It all gets tossed in the washer together in a devil-may-care fashion. The first time this idea was presented to me, I was in shock. My mother taught me to sort out all the loads: whites, lights, darks, colors, towels/sheets and so on. As I've mentioned before, I like to follow the rules; in fact, like a Pharisee I expanded the rules for myself, adding more categories. Pure white! White with printing or design! Light! Medium! Bright colors! Muted or soft colors! Red! Black! Dark! You get the picture.
What this meant was that I constantly had piles of sorted laundry all over the basement floor. This wasn't such a big deal when the laundry was in the basement, but when it was on the second floor with the bedrooms, basically in a closet, this would mean laundry all over the upstairs hallway.
So my method is this: ideally, I do one load of laundry a day. Whatever is in the hamper that sits outside the laundry closet gets washed together. I've never had any problems. If I have any doubts about color-fastness, I toss in a Shout Color Catcher (often just half of one).
As with any rule, there are possible exceptions. I do wash sheets and towels apart from the rest because I like to use hot water, and occasionally bleach on these items. I usually save up the reds and do them together, because red is the worst at bleeding. (I'm editing here to add that if I have a brand-new item, or something that I know will bleed, I will wash it separately first.) And finally, if I have not been on top of things or the family has been very busy and there's more than one load's worth in the hamper, I will probably, but not necessarily, divide it in a very non-strict way into lighter and darker. That's it. Works for me!
Rocks in My Dryer and check out the other great ideas those smart ladies have.