Hey,
If you only need traffic statistics from your spoke site clients then you only need to enable insight on the spoke network as the hub site will not gather data for remote sites.
Here is an excerpt from the documentation on this topic:
MXs that are acting as Auto VPN Hubs will not be able to analyze traffic arriving over the VPN from Spoke sites. To gather data about traffic from Auto VPN Spoke sites, Insight must be enabled on the spoke MX. Finally, traffic originating from the WAN, such as that destined for an onsite web server will not be tracked.
I hope this helps 😉