Yes, each DataPoint would be a part of the same Line series, the only difference is that when using categories the chart treats data as a sequence of non-numerical text labels. You couldn't sample the data down as each point is important, however, when you have a large data set and you do not wish to display all of the labels you could use the LabelStep property, which displays 1 from X number of labels :
RadChart1.DefaultView.ChartArea.AxisX.LabelStep = 10;
This way if you have, say 100 DataPoints, you would only have 10 labels, so you could avoid overlapping of the text. Alternatively, you could always use the manual axis range when needed.
the Telerik team
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