A cursory review seems to indicate that indexed records focus on baptisms, marriages, and deaths/funerals.
This entry from the "Membership Roll" of the West Point Methodist Church (West Point, Illinois) contains brief information on Ella Tammen.
Despite the typed name which should be easy to index, this item does not appear in the Ancestry.com index as of the date this was written. This item was only located by manually searching the entire roll for the West Point church. There were entries for other families of interest who do not appear on the index. A search for the last name of Neill only resulted in a few results (despite the fact that there are nearly fifteen individuals with that last name who appear on the membership rolls of the West Point Methodist and Stillwell Methodist churches). A search for the last name of Rampley resulted in no matches despite a number of Rampleys who were members of either the West Point or Stillwell churches.
It appears to me that this index is not an every name index. While manual searches are usually suggested even when indexes include every name, a manual search is especially warranted in this case given the apparent nature of the index.
Note:
Ella Johanna Tamen is the sister of my great-grandmother Trientje (Tena) Janssen (Johnson) Ufkes (1895-1986). Locating her makes an excellent point about stumbling on unexpected items. I was actually looking for members of my paternal families (Neill/Rampley) in these records and did not even think that Aunt Ella would appear in these records.
