I've learned the importance of testing colours within their specific contexts. For example, the initial colours I thought would work well didn't work with the given wireframes or the desired vibe. It's crucial to always test colours in their actual settings, as well as to consider accessibility contrast ratios and colour blindness requirements.

Usability testing is always essential, as designers often assume certain features will benefit users, but in reality, users prefer having control over their decisions. For instance, in Insight #3, automatically changing screens confused more users than anticipated.