One mxd per region or many mxd's per map
I am working somewhere where they insist on using one mxd per region, in this mxd there is every layer required to make maps (about 10 per region). I find it tedious because you have to turn layers on and off and recreate the legend, and I find that since each region has the same layers if someone has another mxd open I can't edit layers.
What is the best practice? the idea was that there were too many mxd's being created, but I always thought it was better to have one mxd per map.
we can't do data driven pages because each map has about 3 layouts and requires some fiddling that can't be automated.
What you describe sounds to me like a use case for Data Driven Pages.
If they do not meet 100% of your requirements then they are well integrated with ArcPy to complete the necessary map automation.