I keep hearing about folks worrying about colors bleeding and can say I must be bless because when I buy fabric I come home and put several yards at a time in the washer with no problems and have yet to see any of it bleed.
I could not see myself washing only one fabric at a time. It would drive me nuts with all the time it would take to wash several yards of fabric every time I go out there and buy and have to spend several hours doing so or perhaps even a few days.
I use the hand wash cycle on my machine and will run several yards at a time and use the warm setting with a little bit of liquid soap.