The easiest (?) way to handle this is to to think about what happens to "regular" folks going the same way. Are they sometimes attacked by monsters or bandits? If so, the same could happen to the PCs. If not, then it should not be an issue for the PCs either.
I do not think you game should be ruled by dice, it should be ruled by you, the DM. If you think their should be an occasional "random" encounter - put some in. Add in true randomness if you want (it can be exciting for all concerned), but try not to let dice rule you game - most of the time it really is more fun if you don't.