No, reset_target() does what it says: it resets the target; it turns it off and back on again. As I said it looks like there is an issue with your firmware that causes it to stop responding properly after 580 captures. Resetting the target is a band-aid solution. Now that you know that this is happening, the proper solution would be to debug your firmware to figure out the root cause and fix it.
Capture speed depends on lots of factors: the duration of the target operation, the length of the commands and responses that get sent/received for each capture, and the number of power samples that get collected. 14 iterations/s is not an unexpected number.
I’ve already explained how to speed up captures on your other thread.