In both instances, it's absolutely critical to provide as much information as you can so that the chances of success are greatly increased. A thoughtful genealogy query is just as important as other steps in the research process such as determining your objective and identifying key sources of information.
As I mentioned in a previous post, I learned from church marriage records the names of my 4th great-grandparents. Church records are an invaluable resource in genealogy research, since they often provide parent names and the town where an ancestor lived before coming to the U.S. By providing all of the information I knew, a wonderful volunteer found the answers I needed.
My research goal was to learn: 1) where my 3rd great-grandparents, Peter & Barbara Steimer Klein, lived in Germany, and 2) the names of their parents. I knew that they were Catholic and hoped that church records would have the answers. For the archive volunteers to find what I needed, it was important that I provide clues as to which parish they may have belonged.
I knew when and where their first child was born (which helps narrow the range of their marriage year) and that the family later lived in the South Side neighborhood of Pittsburgh. If I would have stopped with that information when I filled out the research request form, I would have learned only half of the answers. The research report showed that Peter & Barbara did in fact get married at St. Michael's on the South Side of Pittsburgh, and it provided the names of their parents. So my 4th great-grandparents are Peter Klein & Eva Dani and Clemens Steimer & Barbara Eid.
However, on the research form, I also provided information about Barbara's brothers. My hope was that, if her marriage record couldn't be located or if it wasn't detailed, the brothers' records might be more helpful. Bingo! Barbara's brother, Jacob, was married in McKeesport, and his church marriage record confirmed that their parents were Clemens & Barbara Eid Steimer. But it also showed that Jacob was born in Wiesbach, Germany. Therefore, I now know where some of my ancestors were living during at least one key event of their lives.
Even if you think a detail is unimportant, it's definitely better to include too much information than not enough. It may make a huge difference in discovering more about your ancestors.