Image Capture Interval Timing Question

Morning,

tl;dr

How to best determine the capture interval using information from Map Pilot for an unconnected external camera?

I have a question about the flight duration and image quantity calculations in the app and how they relate to camera trigger intervals.

I'm utilizing Map Pilot for flight planning of missions using a P3A with an UNCONNECTED external camera attached and connected to a RPI zero. The RPI sends the shutter signal at a set interval to the camera.

How can I use the flight duration and image quantity to best estimate the image capture interval?? I could use the camera params, altitude, flight speed, etc. to script out the time between image acquisitions, but I figure Map Pilot is already doing this in some way, shape, or form.

I notice that the flight duration when I plan a mission without the P3A connected is different than when the P3A is connected (and the home point is set to the P3A's location.) So, I presume the flight duration calculation when the P3A is not connected is based ONLY on the flight time of the mission from the beginning point (green) to the ending point (red)? If not, please explain.

Thanks!
Austin M