In regard to when it really is a good idea to break a project into sub-projects, I don't recall a "rule of thumb" in DAs book. But maybe there is one that someone knows about or maybe we can pool our knowledge here. I have noticed that when I review the projects that I am not progressing on, it comes to me that I was trying to do something that was really a higher level goal. For example, for a long time I have had "I am optimally fit and healthy for my age" as a project outcome. But, all I do is work on machines and I need to have a variety of work outs, follow a diet, keep up wth certain lab tests and pursue a "sociable" sport, which in the end are four projects. As to the sport, I can see there are really two projects, one is to find people with whom to play and the other to find equipment that suits me. For another person this might be one project but I have to look far and wide to find equipment that suits me. When I had a relative in a nursing home, my project goal was to make her time there as humane as possible so I needed to make visits to her, obtain items both to decorate her room and give her mental stimulation, and attend meetings with the staff. But, I did not realize at that time that these were really three different "lines" of work. I am thinking that if the project is very challenging because it is new to you, or so complex or even unpleasant in places, then maybe sub-projects are needed. So the first guideline might be, make sure that you really have a project and not a higher altitude goal. The second might have to do with your comfort level with the processes or the perceived challenge. If the challenge is too great, I think it might be wise to subdivide and this will vary by individual and then change with experience. Maybe another has to do with logical divisions regarding skills, so a little question to ask yourself might be, "If someone were writing an idiot's guide to _____ (the outcome), he or she would probably write separate chapters on ____, _____. etc. Also, to achieve the desired outcome what steps are unique to this project or novel for me, and what steps are part of something that either is done regularly (you just add them to exisiting routine) or needs to be done regularly (may need to create a separate project to create a habit or routine). In your case, I think you will probably need to have routines for following leads because you will hopefully have many.
