CIS - Multiple symbols per library or single symbol per library

I admit, I do have an Altium background but I'm trying to figure out how CIS exactly works. I figured that it is very similar to Altium's DbLib feature, in fact, they seems pretty much the same. 

I'd like to know what the preferred way to handle schematic symbols is. I have seen that for Allegro PCB it is one footprint per file with the footprint name being the filename without the dra extension. This is also how we did it with Altium. For schematic symbols, I have seen that basically all symbols are stored in a single library file (or some number between 1 and 10) but not one symbol per library file (olb). Back then, we kept one symbol per file to nicely integrate with version control systems. It was always possible to determine when a symbol had been changed (and if).

I am not quite sure yet, how schematic libraries are being found. I found a reference to [Part Library Directories] which contains the location of our 3 library files. Does Orcad browse these libraries? How does that perform for .. say .. 1000 files with one symbol each?

If that is unfeasible, is there another way how to best integrate libraries into a version control system?