Here is what is required to make sure we as a fellowship complete that 10th chest. Everyone in the fellowship needs to get to personal 1600 points. There are few strategies you can use to get there:
Strategy #1 - 6 provinces all 6 rounds (TOTAL POINTS = 1620) - Least amount of resources needed but might be hard to do for some because of the timing.
Strategy #2 - 8 provinces for 5 rounds (TOTAL POINTS = 1680) - A bit more resources but more achievable for those who are time limited
Strategy #3 - 10 provinces for 4 rounds (TOTAL POINTS = 1560 - falling short by 40 points) - For those who are even more time limited or know that they will be away for couple of days.
Strategy #4 - 15 provinces for 3 rounds (TOTAL POINTS = 1620) - For those who know that they will be away on a trip or extremly time limited!
Now that you know how many provinces will get you to those 1600, you can figure out which of these strategies fits your game play best and if you can achieve it with you game play or you need to adjust.