Daily date heading frequency only goes to 60

Question:     

We use milestones for schedules and also for machine timing charts. When doing timing charts, we usually use 1 day as equal to 1 second. When cycles are really short, then we use 1 day equal to 1 millisecond, so 1000 days is equal to 1 second. We have a header type (within Date Headings Dialog Box) of Daily 1,2,...30, 31,32,33... Even though the frequency settings allows entry of numbers above 60, it seems to not change anything on the header. So the time breakup in header for frequency of any value above 60 is always 0----60---120---180...... and is not readable due to everything running together. Is there a way to change this so that the header is 0--250---500---750---1000?