Is the issue the scale, or is it actually what the stacked bar represents?
From your example, it seems that you want a bar (not a stacked bar) that shows the average duration for all customers of that category. So for strategy, the bar would only reflect 11.23 and would be a single color. Is that correct?
I know I could do only one bar, one color with the average of the clients per category , but then I would be missing the visual information of how many clients comprise that bar.
So to answer your question , I think the issue that I have is in what the stacked bar represents (I want it to represent the average of that category) but I dont just need it to be one color , I want every customer to be represented by a color in a percent proportionally to the total of that category.
In other words something like this: