From their website:
"There’s no doubt all-over printing is awesome. The ability to print anywhere on the shirt is really a liberating aspect for designers, consumers, and vendors alike. It is important to be aware how the quality of these prints differ from screen prints created with a standard press.
Printing over the collar and shoulder seams is really popular, especially with retail inspired designs. If you lay a shirt down flat, you’ll notice how it is not smooth and flat in these areas. For this reason, when the squeegee passes over collars and seams, the ink is not applied smoothly. In these areas, ink has a tendency to skip or pool. This is completely acceptable and expected.
Since the coverage area on all-over prints is so great, we use soft-hand inks. Primarily, we use chino and fashion soft bases. Water-based and/or discharge inks can be used but there are drawbacks to those inks and they do not work with all designs."
Read more at: http://www.sharprint.com/screen-print/all-over-printing/