You can select various time intervals for the "My Training" graph on your profile page on PowerCenter (stryd.com/powercenter/profile). If you select a time window between the last 6 months and the last 3 years, PowerCenter will show RSS bars that are the accumulated stress per week. When hovering over the RSS bars, you will see your 6-week average stress.
For the 6 weeks average RSS, Stryd uses a weighted average which is different than a simple average for the 6 weeks.
If you have additional questions, contact firstname.lastname@example.org.