Last week when the Slack redesign rolled out, my knee jerk reaction was almost visceral hate.

It felt almost offensive to me to have my entire workflow was upended without warning.

It took me a frustrating hour or two to figure out how to clear the backlog of notifications.

Now that I'm feeling a bit more calm, let me try to abduct some insights out of it.

There's a difference between a tool's interface and (data) quality.

Interface could mean your API or your UX.

UX = API for a computer to human interface

If you change your interface customers might get frustrated ("why did this change? It worked perfectly fine before and now I have to spend unexpected time figuring it out").

If you improve or degrade quality, e.g. fewer errors or better ranking, then the interface doesn't really change and you don't need to alert anyone.

If you add a feature to the interface users might not notice or be bothered by it.

For APIs this is likely mostly true.

For UX though it's much less likely to be true.

Because we have peripheral vision, anything on screen that changes might catch a user's attention.

So most additions in UX count as interface changes.

Interface changes are harder to hill climb and experiment with because you need to coordinate with your users who likely would prefer things to just not change.

With quality changes you can hill climb easier, which gives you a better self-steering north star.

Of course, the quality can change so much that it's effectively an interface change ("this workflow that used to work now fundamentally doesn't") but generally small quality deltas, or even large quality improvements, are fine.