With regards to M&R macs it varies from older models to new FYI. That said, central works and has worked for many if not most, with the occasional shim on the PLS/UB; as the viscosity/rheology of, for instance, a high viscosity long shear ink may require more time to release than a low viscosity short shear. Confused? I won't mislead you by telling you not to be. For instance, a slightly slower, longer print stroke can often achieve desired results without adjusting the off contact or double stroke. Did I not mention mesh count selection, squeegee selection/parameters, and how they all affect eachother? Its all about the release of the ink to substrate (assuming cure issues are under control). Think of it in three parts...
the ink, the transfer mechanism (screen) and the substrate. If all those parameters are dialed in then your life shall be simple.
Guess I may have an article to write after all