It's not very user-friendly to have 600 values displayed on one chart without scrolling, IMHO. This is why Qlik has developed this "scrollable" option. I agree that they should give us more options to handle it, but this is brand new product (kind-of) and few things are still not optimized.
You can do couple things here:
1. Keep all X values and "Maximize" the chart to see all X values (it might work if you have high screen resolution).
2. Change your Dimension so the chart will display every 10th point (for example). For your line chart it should work pretty well.