Ah right, makes sense. In that case it probably fine to just mix it up. But if you want old whites to pop a bit more, using a detergent for white stuff works well.

Personally I use a special detergent for blacks and darks and also the dark program on the washing machine. I’ve found it greatly increases the life of black and dark stuff. I almost exclusively wear black and dark blues and want to use clothes as long as possible.