Since genealogical research is highly individual and expectations and goals are internal rather than imposed by society, how do you measure "success?" Since any definition I would attempt would be based on my own criteria, I suggest that instead of looking at genealogical research as a united activity, that you (we) all become more task oriented.
If you were to start a weight loss program, you would likely consult some standardized Body Mass Index to give you an idea of your "ideal" weight. If you were going to run a marathon, you would be pacing yourself and comparing your "times" to what was expected from your age and condition. Genealogy is a different type of activity. It is not competitive and there are no standards to give you an idea of what you should accomplish. If you examine you expectations in beginning a line of genealogical research and then set a goal that is short-term and realistic, you can see progress and feel success despite the lack of an absolute standard or comparison to other researchers.
For example, I presently have a goal to digitized thousands of photographic negatives and prints from my Great-grandparents. This is a task with a beginning (acquisition of the negatives and prints), a clear activity (digitizing the images) and an end, turning the images over to a university-based repository. I can easily measure my success in that project by simply finishing the objective. So, if I break down my research and organizational expectations into manageable goals, I can "succeed" each time I reach a milestone.
In every case, goal selection is critical to how we view our progress and it is fatal to a sense of progress to measure our success in comparison with someone else or the progress made by other researchers. For example, I could easily add 10,000 names to my database. But why would I want to make that a goal? Why not have a more meaningful goal such as, adding images for as many ancestors as I can find? In my case, adding the images would be more useful and measurable. Adding another 10,000 or so names to my file, using existing online databases would be a waste of time. In this example, it is absolutely important to divorce ourselves from the idea that success in genealogy involves the acquisition of large numbers of names.
One of the biggest mistakes in genealogy is allowing others to determine our success. This issue is illustrated by two of the most commonly asked questions from non-genealogists when they finally understand what we are doing; first, how far back have you traced your genealogy and second, how many people do you have in your database. From my perspective the proper question that should be asked is how well documented is your research? Neither of the first two questions are in the least relevant to research.