Interesting but perhaps a misleading title. I can't see it taking less time to set up an eccentric-only exercise - it's simply quicker to perform the concentric component to get back to the start position of an eccentric component. Perhaps with purpose built machines this benefit could be exploited. The most immediate application I can think of for this would be lowering down from pull-up position using foot-platforms - step up onto the platform, lower down to full hang, then step up again. This could be of actual benefit, costing no more time and done with no modification of currently available equipment.