How does skiplagged work?

[kasaam]

I read it uses saved data,that would mean that pokemon have a fix spawn time depending on current day and time. So is this true someone tested it? Is it every day the same or every week?
Would be nice to know because i live in a rural place and rare pokemon are rare here...with this method it would be possible to make a notice if a rare pokemon spawns and catch it again the next day/werk on the same spot at the same time