Part Two: The product · Trouble and change
Makers see the old design's faults every day and want to fix them all at once. The people who know the product best pay the most when everything moves.
A person who uses a product daily stops reading it. Their hand goes to the top right for search and the third item down for reports. That knowledge took months to build, and it is a large part of what the product is worth to them. The makers cannot see it. They see only the screen.
What the makers do see is a design with five years of compromises in it. The navigation grew one request at a time. The colors are dated. A redesign would fix everything in one release, and it would be something to announce.
So the new version ships. Newcomers find it cleaner. The long-standing customers, the ones who pay the most and recommend it to others, arrive on Monday unable to do their jobs. Every habit now points at the wrong place. They are slower than a beginner, because a beginner has nothing to unlearn. Where a company has trained its staff on the product, the redesign is also a retraining bill that nobody there asked for.
Windows 8, in 2012, removed the Start button that people had used since 1995 and opened on a full screen of tiles. The button came back a year later in Windows 8.1. The Start menu itself returned in Windows 10, in 2015.
A product still has to change. The cost of each change is paid in other people's habits, so it should be spent a little at a time, on things that matter.
Say what changed and when. A dated note inside the product, in the customer's own words, tells someone back from a week away why Monday looks different.
Therefore:
Leave things where people have learned to find them, and improve the product in pieces small enough to absorb in a day. When something must move, say so beforehand and leave a pointer in the old place.
In practice. Before a redesign, list the ten things regular customers do most and where each lives today. Any that moves needs a reason stronger than "it looks better."
Goes with. Small repairs in place are FIX WHAT'S THERE FIRST (25). When a feature has to go altogether, see TAKE THINGS AWAY (27). A product that follows THE SAME THING WORKS THE SAME WAY (84) has less to redesign.