Well, I wouldn't say that, but some data is more easily handled than other data. If you have a uniform spacing on the date axis, and can convert times to decimal form, it would be easy. I did a quick graph of sunrise and sunset for my location for the year (data from Wolfram Alpha):
For the Y-axis, I'm just plotting the hour + (minutes past the hour/60).
I do think it is appropriate to take note of the word "sketch" in the application's name and set expectations accordingly. It isn't a fully fledged scientific plotting package by any stretch of the imagination, but it is a handy graph sketcher.