Should I use Garmin Calendar or TrainingPeaks?
TrainingPeaks is the recommended option. If you use TrainingPeaks Free, iCal export is included. Garmin Calendar export is also supported as an alternative. Simply paste your iCal URL in the Setup page.
How often does HotSync refresh my calendar?
HotSync automatically refreshes your calendar daily at midnight (your local time) when auto-sync is enabled. You can also manually refresh anytime using the Refresh Calendar button on the dashboard.