There are four basic time scales that PCs deal with.
- Rounds for combat.
- Turns for exploration
- Watches for wilderness travel
- Haven turns for downtime actions.
These are meant to be general outlines rather than hard rules, of course. This is more or less the rate that situation-specific actions can be taken. Switching from one scale to another should be smooth and easy. They are meant to simplify after all.
Combat Rounds are a couple of seconds. Enough for a single action, a sprint across a room, a few lunges and parries with an enemy, grab something from your backback, etc.
Exploration Turns are 10 minutes. Mostly for dungeons, but any place the PCs want to take their time. This counts as being cautious and watching for traps and taking in surroundings enough to map more or less accurately. In pure game mechanics, this is the period of time that a party can cover 10 squares on a traditional 10' squares grid and is also the rate that the DM rolls a chance for wandering monsters. So, entering and searching a 30×30 room is a single exploration turn.
Watches are the rate of things happening while going long distances. Random encounters on the road and such. How much distance gets covered is more dependant on the terrian and weather and other factors, but is expressed in Miles per Watch.
Haven turns occur anytime the players return to some secure home-base after an adventure, usually a town, or player-owned citadel. The turns don’t actually last one month, they just sorta “round out” the month to some unspecified degree. So, if the players adventure in May, then return home for a haven turn, their next game will take place in June, regardless of whether the previous adventure lasted an hour, or a week. Basic idea gotten from here. This is where crafting, research, training, and all other 'downtime' activities take place.