Change x axis grid line spacing/labeling

Grafana v10.2.3 via the cloud/web interface.

I’m graphing a time series, specifically a weekly one. Obviously I’d prefer that the x axis have one gridline per week, labeled for that week. But Grafana is setting automatic gridlines and labels at completely arbitrary dates, and even changing based on the window size.

That would be useful in other circumstances but is obviously a problem here. How can I override this behavior and get the panel to only display one gridline & label per week?