I like to think "respect the nature of the fabric" and handle accordingly. I sometime use blends but have to be careful as they can even shrink with a hot dry iron as they tent to "melt" somewhat. So just be careful in handling.
Some years ago a blend of cotton and rayon was readily available and worked good in quilts. I try to keep the weight somewhat consistent. 80% poly and 20% cotton is especially difficult sometime when used with 100% cotton.
So just handle according to the needs of the fabric. Those poly/cotton fabrics of the 80's are still holding up in both color and stability.