It's not a simple issue and different developers have different preferences. For new users, keeping all your tables in one file is probably best as that simplifies a few issues.
Some developers split their files into two parts. Part one has all the layouts, scripts etc that make up the user interface and part two has just the data tables. With that option, they can deploy an updated interface file and not have to import any data from the existing solution.
Other developlers group their files into modules so that they can mix and match modules for different solutions and updates may require just importing data from one file's table instead of the whole table set.
On the other hand, this can make for a much more complex system to manage and you have to be careful of any changes to filenames and possibly where they are located so as not to "break" the external file references.
Thanks - the lady I'm working with decided she wanted them all together - she is brand new to FMPro. So that's what we're doing. i appreciate your description of possible scenarios.