I've see all six "sources" used in this instance. The Ancestry.com tree indicates that all six are sources for the fact that this person was born on a certain date in a certain place. The problem is that all six sources do not say that. Tying these sources to a precise date and place of birth is indicating that they are more accurate than they really are.
- The 1900 census provides a month and year of birth along with the state.
- The 1920 and 1930 census provides an age and a place of birth. The age does not necessarily suggest a specific date--which this citation seems to indicate that it does.
- The death index does provide the date and place of birth.
- The U. S. National Home for the Disabled Volunteer Soldiers provides an approximate year of birth and a state of birth.
- The World War I draft card provides a county and state of birth along with a date of birth.
- Month and year in Illinois should be tied to 1900 census.
- Approximate year and location of Illinois should be tied to the 1930 census and Soldier's Home information.
- Specific date and specific place should be tied to the death index.
- The approximate year and county and state should be tied to the draft card.