Sarah ... is this the quilt that we both made from the Oh Frassone blog??
yes to others ... the batting determines.
Yes the batting instructions are for circumference measurement, and generally if I am going to quilt linear only I will cut the minimum quilting recommendation in half.
If you are quilting 3" apart linear you should be find quilting in one direction only. You can even get by with 4" or 5" apart.