The code attached to the file name was just a way of keeping the records separated by file name.It would not have any thing to do with FTM.
I don't attach media to FTM.My file with a little over 1600 people is about 14 mb. Since there are over 500 marriages, assuming 4 census images per marriage, if attached, the FTM file would double or triple for the same number of people.
I prefer to keep FTM for notes on the family. In my FTM file they can become two and three pages per person.In addition there are the summaries to justify connections in the family books.
I do keep all census and other documents associated with the family in PDF files in a logically laid our system of folders, so I can easily find what ever document I am looking for.