Hello Chirrueluez77
The answer is given here:

https://www.sbb.ch/en/help-and-contact/my-travelcards/travel-without-valid-ticket.html
Travelling without a ticket is an official offence and against the PBG law. The transport companies can take you to the court at any time, not only after the third time.
Whether you will get a criminal record is the decision of the judge, taking into considerations other possible violations you have committed in the past.
I wondered if you would be OK with the fact (and consider it fair) that the clients of your employer (if you are employed) are not paying for your work, and you consequently do not get your salary, although you worked hard to accomplish the service requested/expected by the client.
Kind regards,
Roland