Are you using XCategory or XValue? I think that if you use XValue you shouldn't have such problems (by keeping the x axis AutoRange=true).
If you use XCategory - then the axis wants to show each category because categories are meant to be totally different - such as "Apples", "Carrots", "Tomatoes" and so on. And this is why you get a label for each data point.
I would generally suggest updating your project to work with XValue. If it is not possible to switch to XValue - then iterating through all the series and counting the data points is the only way to go.
the Telerik team
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