A recent model for the drop-on-demand (DoD) jetting of mono-disperse linear polymer solutions has identified three regimes of behaviour: with the polymer chains fully relaxed; with significant viscoelastic effects; and with the chains fully extended. These regimes have now been confirmed by experimental observations in several different systems. The model predicts the maximum jettable concentration of polymer as a function of molecular weight. The highly extensional flows in high-speed jetting with viscous solvents can fully stretch linear polymer chains outside the nozzle, permitting jetting of solutions with higher polymer contents than for purely elastic behaviour. These results are significant for DoD printing at high jet speeds and will be relevant to jet formation from linear polymer solutions for any DoD printhead.