Maybe you should try prerub/ presoak test.
I do this sometimes when i am worried but really don't want to wash.
First, i rub a corner of the fabric with a soft white rag to see if color "rubs" off. For sure if it rubs off it will bleed off.
Then, I put a little laundry soap and really hot water in an old container i keep....and add a 4" square of fabric. If it bleeds when i swish it around a bit - i wash it....if not, i roll the dice and use it without washing first. Then use color catchers in the wash.
Also -- i always fill the washing machine at least half full before adding my quilt.