I suggest doing some test runs
Thank you mate..i will try to visit the gopro labs and run some tests1 photo per minute is too much. but it depends on the lenght of the final video you are expecting.
Personaly I would go either 1 per 5min ( 4min of video) or 1 per 30min (around 40s of video?) , anything else would be excesive imho.
Also look into gopro labs firmware, there are some advanced timelapse features which i havent played with but there are some features exactly for your need.
As Fish has said, do some tests for a day to see what frequency would be the best for you.