Just make sure you're loading the shirts on the platen correctly.
I've done this but I've found it doesn't really solve the issue of shirts that get a little askew from top to bottom. Sometimes the bottom of the shirt will be corkscrewed by just a tiny bit and because you don't have sleeves to use as reference points at the bottom of the shirt, it can lead to a skewed print. I try to use the seam but that can be hard to eyeball, and the direction of the fabric can be tilted to start with. You just have to load it right by holding the bottom at the edges.One quick and easy tip is to get a marker and draw a vertical line down the center of your platen. Use that as a guide then loading, flattening and straightening a shirt.