The question is already on the topic. How many spins does a system has do endure to be considered a good system while testing? 10.000? 50.000?100.000? What do you think?
I test mine with 100'000 spins, as 1 spin per second is about 11 days of play if I remember well.
And yeah, 1 spin per second because I code bots.
It depends on how many spins you intend to play.
A rule of thumb is to expect profits for the first half of the amount of spins tested, then the other half, consider yourself "at risk".
Then,
Playing past the amount of spins the system was designed/tested for is suicidal.