I had a thought for a hexcrawl procedure. This relates only to calculating distance travelled, and obviates the need to keep track of the distance travelled within a hex.
1. 6-mile hexes.
2. Good roads generally speed movement and help with navigation; poor roads help with navigation only.
3. Entering a hex using a good road takes 6 units (miles) of movement. On plains and the like without a good road, or rougher terrain with poor roads, it takes 8 units of movement; difficult terrain takes 12 units of movement, and very difficult terrain takes 20 units.
4. Calculate the distance that would be travelled in ideal conditions in miles, given the movement rate and time spent travelling. Assume base unencumbered rate for humans in whatever system you are using is 3 mph.
5. Figure out how many complete hexes could be travelled, subtracting the movement value for each hex from the calculated distance.
6. If there is a remainder, roll a die of the same value as the movement value of the next hex. The remainder is the chance of entering that hex.
7. If the party isn't happy with how far they got and want to travel longer, deduct each extra mile from the original roll to see if they make it.
For example, a 1e party is walking with a movement rate of 9" (because they are a UA party with fighters in full plate, and fuck "plate mail" movement). They travel for 8 hours at 9/12 of full speed, so 3 mph x 8 hrs x 9/12 = 18 miles under ideal conditions. They take a good road to the next hex, which uses up 6 miles of movement. They then travel cross-country in plains, which takes 8 miles of movement. They have 4 miles of movement left and want to go into the hills, which are difficult terrain and would require 12 miles of movement. Roll a d12; on a 1-4 they make good distance and enter the hex; on a 5-12 they don't quite make if before their 8 hours is up. Let's say they roll a 8, they will need to travel long enough to add another 4 miles to make it where they want to go, which would take 4 miles/3mph/(9/12) = 1.8 hours.
For modern/sci-fi, use 10 km hexes, assume base 5 kph movement rate, good roads take 10 km of movement, good terrain with no roads takes 12 km, difficult terrain takes 20 km and very difficult terrain takes 30 km (you do have a d30, right?).