At the 200 - game sample size, you would need a winning percentage in the low 60 % range to prove statistical significance. (sportsinsights.com)
An eight - game sample holds no meaningful predictive value, first half against - the - spread records can not predict second half against - the - spread results. (betlabssports.com)
That said, I think this ~ 100 game sample system should be profitable going forward although I wouldn't expect the 66 % win rate to hold up. (betlabssports.com)