The motivation for continuouscolumnar pinning centers has been to provide maximum Upin. It has been assumed that this provides the best Jc and Bpin. Limitations on Jc and Bpin observed for columnar pinning have been attributed to degradation of the order parameter and Tc. We examine columnar pinning by ionic damage and conclude instead that geometrical effects of columnar pinningon percolation path and on the number of pinning centers are the dominant limitations of columnar pinning, leading to a limit of Bpin～4 T. Evidence suggests that multiple-in-line-defects (MILD) are far better suited to increase Jc and Bpin. The morphology of MILD pinning is reviewed. Ion energy loss per unit distance, Se, is found to be most promising in a regime almost diametrically opposite to that sought to maximize Upin. We expect Jc～106 A/cm2 and Bpin>40 T from MILD pinning,despite sharply decreased Upin.Experimental confirmation is proposed.