This is related to the question Why would a family baptise at a parish but not marry or bury there?. If you've exhausted all the records available to you for a parish, and you want to widen your search, how can you tell if you've traveled 'too far' in your attempts to make an exhaustive search?
Some local travel information can be found on websites such as Devon Heritage. But how do we take these materials and put them into the proper historical context?
In the US, research guides often suggest the use of topographic maps like the USGS Historical Topographic Map Collection. In the UK, one can access Ordnance Survey Maps - Six-inch England and Wales, 1842-1952 at the National Library of Scotland or the historical maps available at A Vision of Britain Through Time or http://www.mapseeker.co.uk/ .
Historical maps are a great resource, but how do you get a feel for how people commonly travelled, and how far was 'too far'? Obviously it varies with economic status, as we can see from this exchange in Jane Austen's Pride and Prejudice:
"It must be very agreeable to her to be settled within so easy a distance of her own family and friends."
"An easy distance, do you call it? It is nearly fifty miles."
"And what is fifty miles of good road? Little more than half a day's journey. Yes, I call it a very easy distance."
In my husband's family, I have several instances of census records where grandchildren are listed in the households of their grandparents, nieces visiting aunts, and so on, so the family connections quickly become evident. In the US, I also have several notices from the gossip-filled small town newspapers which list which family is visiting and from where. Without those hints, how can you tell if you have strayed past Elizabeth's, or Darcy's, "easy distance"?
Note the distances children were allowed to travel alone in this article:
The generations who walked everywhere would, it seems to me, have a much different sense of distance than those of us raised to go everywhere by car. City dwellers would likely be different than those raised in rural areas, etc.