Cycle a fresh build every 60-75 days so you never hit the wall mid-testing. Internal testers (up to 100) don't count against this, only external testers do. If your build hits day 90 and you're not ready, upload any incremental change (version bump is fine) to refresh the clock.
Help me set up a TestFlight build-refresh schedule so I never hit the 90-day external-tester wall. My current build went live on [date]. Give me the dates to upload a fresh build, remind me internal testers don't count, and turn it into a simple recurring reminder I can follow.