Within iOS 13, the "Find Friends" and "Find iPhone" apps have been merged.
Prior to iOS 13, I rarely used the "Find Friends" App, as it rarely really seemed to update the location of the various i* devices that I have, instead I used the "Find iPhone" which appeared to work almost in realtime - so was regularly using that to track the whereabouts of my Kids.
Now, the newly merged iOS 13 version - would appear to be just like the old "Find Friends" App - and does not update the device location frequently.
One reason for this, I suspect could be a power-saving feature upon the devices sharing their location. Though a thorough investigation to determining what exactly is blocking the sharing may take too long - it'd probably be a lot quicker to get Apple's response.
A simple experiment - for example, with an iPad using (iOS13 too), in "Sleep/Power-saving" mode (darked screen), and It's last updated location shown as 2 hours prior ; using the web version of "Find my iPhone" (https://www.icloud.com/find/), which has a Refresh icon alongside the device symbol, the location would not update until I brought the iPad device out of sleep, and unlocked its screen. Thereafter, however, without the device being moved far, it's refreshed location time would not be updated... (even though at 16 minutes an "Old location" banner was shown in Red above the device, and didnt disappear until I restarted by "Find My" app upon my iPhone).
For a moving device, the Refresh rate appears to be inconsistent, maybe the device has to be actively in use for the location sharing to be active ?
