The chances of that, if those are the only 4 she ever bought, are 1 in 18 septillion - 18,000,000,000,000,000,000,000,000 if your head is wide enough to see all those zeros. But she might know that, thanks to her PhD in mathematics from Stanford.
Lucky numbers? Unlikely, since three of the winners were scratch tickets and one was a lottery draw.
A system? You can bet the third time she showed up at lottery headquarters in Austin the fraud alarms went off but they have found nothing. Whatever the secret, she is not telling, and hasn't said a word since 1993 when she first hit big. But the people around there say she has been very nice, she bought the local church a van and gave her home to charity when she moved to ... wait for it ... Las Vegas. I would too.
A lucky place to buy, perhaps? A highway gas station called the Times Market has become something of a Mecca for people looking to win big, since she has won twice in it, making it three times in the same town of 3,000 people. 525 Highway 77 Bypass, in Bishop, Texas if you are getting in the car right now. I'll meet you there.