It's easy to do so provided the equipment is properly aligned and calibrated. Whenever I goof one it's due to me being exhausted and groggy. And now most serious pro frame shops have computerized matcutters that could turn out hundreds in a row perfectly cut as prescribed. Many of AA's prints I've seen displayed had rather clumsily cut overmats due to improper technique. Sometimes such problems arise because people assume they're starting with properly squared board, yet haven't actually checked it with a square first. Allowing a half inch margin of error is like wondering whether or not you can hit a bull with a 12ga shotgun from 3ft away. What I'd really like to have is a non-computerized Esterly Speedmat machine; but I can't justify the expense, so I'll stick with my ole linear cutter for awhile. It might outlast me.