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When we first designed a more modern (!) UI for that system, the current users raised quite a ruckus about us moving their cheese on them. They had their primary workflows scripted completely, and had learned workarounds for an unintuitive, low-usability system:
Type, tab tab tab, type, hit F4, type, tab tab tab tab, type, hit F5, enter.
Things like that. So those old guys were faster on the old system than they were on the new system. That means we should revert, right? But what happens when the only guy at your business who knows how to use that system gets hit by a tour bus, or when you have to train a millennial to use your terminal green screen? And what about even the old user who, after only a few days of using the new system, suddenly finds that they are actually more productive and have fewer mistakes made because of the new design?
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