We spent four months redesigning IndiGo's booking confirmation screen. The old one was a dense information dump — booking code, passenger details, flight info, all crammed together in a layout unchanged since 2016.
The new one was beautiful. Clean hierarchy, breathing room, a delightful 'You're all set!' state with the seat number large and central. Design team loved it. Stakeholders approved it. We shipped it.
NPS dropped 12 points in two weeks.
The culprit wasn't the design. It was the familiarity. The old screen, ugly as it was, had trained 50 million users over 8 years. They knew exactly where the PNR code was. They screenshotted it the same way every time. We moved it.
Lesson: visual improvement ≠ experience improvement. Familiarity is a feature. When you change something that millions of people have automated, you're not improving — you're relearning them. That has a cost.
What we did: kept the new visual design but restored the PNR code to its original position. NPS recovered within 3 weeks. Small compromise, massive outcome.
The Takeaway
Familiarity is a feature. Before redesigning high-frequency screens, map what users have automated — then decide which habits are worth breaking.