Many players do notice that winnings happen more often in demo mode than when playing for real money. But technically speaking, most licensed providers like NetEnt, Microgaming or Pragmatic Play use the same algorithms for both modes. Another thing is that in the demo game, you don't take risks, you play longer, and purely psychologically it seems that wins are more frequent. However, it is important to understand that there are not entirely honest ****s that can “tweak” the odds in their favor. That is why it is important to choose proven platforms. For example, at https://auspokies.net/free_pokies you can find free versions of popular slots and check their mechanics before playing for money. By the way, it is worth considering the volatility of the game - if the slot is initially designed for rare but large wins, then in real mode it will work the same way. So globally the chances do not change, but the perception may differ. In general, testing games in demo - useful, but do not expect that real bets will be as successful as free spins.