.NET Chart TimeSpan Scale

Match Data Granularity
Select time intervals that match the granularity of your data (e.g., seconds, minutes, hours, days, etc.). For example, use daily intervals when displaying data spanning several days.

Avoid Overcrowding
Ensure label intervals are not too frequent to avoid overcrowding the axis with too many labels. The automatic date time step selector in the chart will try to select a proper date time unit and multiplier that will not clutter the scale with many labels but still generate a sufficient number of labels so that the scale is readable.

Choose Proper Formatting
Different time units require different time format strings. For example, it does not make sense to include hour information when generating labels using the millisecond unit.