Recently I found one of those really exciting matches at Ancestry -- one where the person matches you through a single ancestor rather than a couple. The match was on a great-great-grandmother. I descended through her first husband; the DNA match descended through her second. An opportunity to focus on a single line!
The problem, of course, is Ancestry DNA lacks a chromosome browser. I contacted the matching kit manager to see if she had uploaded the raw data to GEDmatch.com. She had not. After explaining what it was and did, she was not interested in uploading at this time.
When I looked at the "shared matches" on Ancestry, I was only able to identify one of the two. That person matched my fourth great grandparents on my two great grandmother's maternal side. The other person shows no known connection to that surname. I'm not currently able to make a connection to the tree although perhaps I will be able to do so in the future to make a triangulation . . . but I'd really love to know on which segment the match is located . . . and whether persons who tested at other companies also match the segment.
I hope the kit manager attends some sessions on working with autosomal DNA and learns the benefit of GEDmatch and discovers whats she is missing by not uploading. I did, at least, provide her with a link to a video by Angie Bush that I hope she'll watch.