User research can be time- and resource-intensive, but there are ways to identify bottlenecks and create efficiencies in your process with scripts and automation solutions.
Users often struggle to find their time zone from a time-zone selector. Where possible, locate users’ time zones for them, organize time zones alphabetically in a dropdown, and allow users to search by city and country.
Users don't work hard enough to discover how to use your design in the intended manner. Bad user! But really, they're just prioritizing their own time and interests and behaving the way evolution made people.
Internal validity ensures that your study design does not favor any particular condition or response, while external validity is about a naturalistic study setup and choice of participants.
10 things you should do when running a usability study. Remembering all the steps leads to good research insights. (The second of 2 videos on usability study checklists.)