
Running from west edge of the map to east edge of the map on foot would take about 20 minutes. Flying from one side of the map to the other in a helicopter takes about 7 minutes.
Far Cry 6 has the biggest map of any Far Cry game so far, with a total size of 88km² (a third of it is water, two thirds are land mass). 30 Hours on Normal Difficulty, doing all quests as you go through each region and destroying all Military Targets along the way. This is how most players will enjoy the game and what will be applicable to most. 20-25 Hours on Normal Difficulty, listening to all dialogue, moderate exploration (50% completion). 15 Hours Speedrun on Easy Difficulty, skipping all Dialogue & Cutscenes, ignoring all side activities. Plus a few more hours for Collectibles and destroying Military Targets. That’s 105 Quests x 15 Minutes = 26 Hours for all quests. Some are much quicker and only take 3 minutes but then others are longer and can take 20-25 minutes.
On average they last about 15 minutes each.
That’s a total of 105 Quests in the game. The endgame region has fewer quests and is much quicker to do. There are 56 Main Quests, 28 Yaran Stories (Side Quests), 21 Treasure Hunts. The 3 main regions take about 5-6 hours each for story alone. Then the whole map opens up and you gain access to the remaining 4 regions. The Prologue on Isla Santuario lasts for 2-3 hours. The more side tasks you do, obviously the longer it will take.
That playthrough was on easy difficulty focusing purely on story without doing any side tasks.