The bit types you are referring to are only one aspect of Ladder Diagram programming. Data is routinely handled in words and double word formats, possibly as floating point numbers. Words may also be used to form shift registers and sequencers. These uses of the device memory space may be compromised in the manners I mentioned.
Many implementations allow accessing of what would normally be used as word memory as individual bits. The opposite is also true. Some allow accesing of groups of bits in a word type manner. All these uses contribute to possible address conflicts which may be difficult to find quickly.
In most cases only rigorous documentation by the programmer can aid in preventing these problems.