Hello!
I would guess that, like in most rpgs, real time is not as important as in-game time.
If we assume this is the case then some math can be done to see how long it takes for time to pass (in-game) when we need to know it.
I assume it is important to know how much time passes during a scenario so here comes the math... Please keep in mind that english is not my native language and that math is not my favorite thing... Especially on a sunday ;)
Let's go!
1 mile = 5280 feet
12 miles = 63360 feet
- that's what a PC can manage to walk a day on open land or roads. 24 hours and after that they fall asleep... Totally exhausted ;)
1 hour = 2.640 feet
1 minute = 44 feet
10 minutes = 440 feet
- now we know how many feet a PC can move at "normal speed" through "normal terrain" before the duration of the "10 minutes spell" is over.
1 second = ~ 0,73 feet
- good to know for the next part
1 turn = 30 feet
-that's what a PC can move in 1 turn if he doesn't "run" (to do so he needs to have a free inventory slot to use the move action twice).
30 feet =~ 41 seconds
- now we know how much time passes in 1 turn.
10 minutes = ~14 turns
- now we know that a "10 minutes spell" lasts 14 turns.
1 scenario = 6 turns
6 turns = 180 feet
- a 2'x2' playing map is 180x180 ft/24x24 in/24x24 squares.
6 turns = ~ 4 minutes
- if a PC does not "run" he could travel from one edge to the opposite edge in 4 minutes.
I hope this was not confusing... And hopefully i did the math right ;)
To put it into context:
Imagine the following situation:
The warband enters a dungeon to gather valuable loot. After they get it they trigger something and an overwhelming horde of enemies rushes at them. The warband needs to escape so a "breakthrough"-scenario is played. Let's say that the first thing that happenes in turn 1 is that a "10 minutes spell" is cast. The warband manages to escape at the last turn (turn 6), runs over a bridge and destroys it to prevent the enemy from following.
They stumble through the entrance of the dungeon and get ambushed by a rivaling warband who waited for them to steal the loot.
A "brawl"-scenario is played and it lasts for the full 6 turns. After that second scenario the "effect" of the "10 minute spell" vanishes.
This hopefully helped.
A 24 hour marsh is a bit unrealistic and 16 hours would make more sense. In the end, time can be a flexible thing. As long as everyone has fun i would not go to hard on the numbers but i know that different playing-groups have different points of view.
I would like to hear why you did ask the question in the first place... Out of pure interest. I would love to know of what situation you can think of that requires to know if time passes in-game or in-real :)
Stay safe and healthy and enjoy this cool game!