This is taking a little bit of inspiration from "The One Ring" game, but fitted to a method that is a bit more "OSR" in nature.
It is also intended to present a little bit of a mini-game that can be dropped in as needed or omitted as needed.
Note that this assumes a known world, rather than a "hex-crawl" where the players explore step by step.
Many campaigns will have regions that are fully explored and frontier regions that are not.
It assumes use of a hex map for travel. Freeform maps can usually be eye-balled to find how many hexes would be in a particular area.
Blame any inconsistencies on bad map makers in the game world or the capricious goddess of travel and direction.
Determine your travel route
The players will determine what route they intend to take, using their own map.
Measure out the number of hexes to be traveled and the expected time required.
The players must factor in any needed food and supply requirements and pack accordingly.
Any terrain other than flat steppe, plains or cultivated land will have a Delay Rating.
Add up all Delay dice together in one pool.
Roll the indicated number of D6 with every 1 causing a delay of 10% travel time.
For example, if you were expecting 40 hours of travel time, rolling a pair of 1's on the delay dice will add 8 hours to the expected arrival time.
Some character classes are more proficient at travelling than others.
Two characters per party may contribute their Travel skill.
Negate a number of Delay dice equal to the total travel Skill pool of contributing characters.
A party of 6 may use the Travel skill of 2 characters.
The two best characters have a 3 and a 1, allowing the group to remove 4 Delay Dice from the pool before the GM rolls.
Travel can be problematic, especially in a world that is raw and uncivilized.
If the party experiences any delay, roll those dice again with a second 1 indicating a problem, challenge, hazard or encounter.
These can range from detours due to impassable terrain, bad weather forcing the party to seek shelter, encounters with enemies or injury to travelers or mounts.
For now, the GM will add these encounters as they see fit. The complete rules will likely include some tables.
A single 1 can be treated as a minor inconvenience or concern, 2 as a major problem and 3 as something that threatens the success of the journey.
If multiple 1's are rolled, the GM will have to determine whether they are combined into bigger hazards or treated separately.
Once the party arrives, they will require a day of rest, recovery and repair of equipment.
Failure to do so will impose a -1 penalty to all ability checks and attack rolls until a day of rest is received.
Note that this is based on completing a journey, rather than the length of the journey and serves to discourage breaking a journey into a dozen small trips to avoid Delay dice.
Typical Delay ratings:
Cultivated, plains or high road - 0
Rough or harsh flat land 1
Hills or forest - 2
Swampland - 2
Mountains - 3
Wilderness +1 (at least 6 hexes from a city)
Enemy patrolled +1
Bad weather +1
Typical Travel skill:
Scouts (rural thief) 1
Little folk (halflings) +2
A character with a suitable ally might add +1.
The party will travel along a high road for 4 hexes, then enter 2 hexes of forest and one hex of mountains patrolled by enemies.
This gives a total of 6 delay dice.
They have a ranger and a scout in the party, allowing them to negate 4 dice.
They will roll 2D6, scoring a 1 and a 4.
This causes a 10% delay and another die is rolled. A 3 is rolled, causing no further hazards.