The Dalemark Gambit
Expanded Exploration Rules
Thoroughly exploring an area requires 1 hour of exploration for each hour of travel. Each character that chooses may make a Perception or Survival check for each hex (or partial hex) explored.
Characters can travel for up to 8 hours per day without risking exhaustion, allowing a maximum of 16 hours combined travel/exploration time and one 8 hour rest per 24 hour period.
There are approximately 12 hours of useful daylight per day, varying by season/weather/etc. Exploring without adequate light imposes disadvantage on Perception and Survival checks.
Exploring uncharted forests, mountains, or similar environments limits traveling to Slow Pace, in addition to any effects from difficult terrain.
All together, this means that a party can fully explore a maximum of two 6-mile hexes per day if they work continually from dawn to dusk, or 3.75 hexes (16 miles) by exploring for a full 16-hr day.
More realistically, a party can explore 1.5 hexes (9 miles) per day while still leaving 3 hours for meals, Short Rests, breaking/setting up camp, and other activities, followed by an 8 hr long rest.
A long rest consists of at least 6 hrs sleep and up to two hours light activity, such as reading, talking, eating, or standing watch. Elves require only 4 hrs 'trance', and can spend the remaining 4 hrs doing light activity. This means that each non-elf can contribute a 2 hr watch shift, and each elf can contribute a 4 hr watch shift, per 8 hr long rest.
Creatures that require more or less sleep are able to contribute equivalently shorter or longer watch shifts.