While 10,000 would be a perfect sample size, I think a couple hundred is considered a decent sample size for an individual doing a test, especially since said sample reveals a pattern. You could easily extrapolate that said pattern will continue and is a safe assumption until someone can come along with evidence to disprove it. While not exactly professional, you do that kind of thing in Highscool and University level Statistics courses.
As confrontational as it was, I do believe Niara was correct in saying that if you wanted to prove her data was lacking or unsatisfactory, it is on you to provide the evidence showing that her data is in fact lacking. Saying her sample size is too small gives you some backing, but to actually prove her results wrong you need to present your own results with the size you stated. If you want us to believe there is no pattern in the rolls I genuinely ask you to show us by doing 10,000 rolls that indicate a lack of pattern.
The more data and tests done the better.