My two cents: many!
One service experience can inspire many Service Design Principles.
A bit like a tree where the experience would be the trunk and each learning you make is each leaf from the tree.
I finished a Service Design Principle co-creation call with my good mate Loris Olivier. He shared with me one service experience he's been through, and from that single story, we could extract 4 principles that could be interesting to explore in more depth.
Not bad for a 45 minutes phone call.
So if you think: "I'm not experiencing enough different things to create my own library of Service Design Principles" take this as a hint that your life is already rich enough for you to learn a lot from it.
No need to travel to many countries and pay for expensive experiences. Just normal life can already inspire a lot.
A community question
This question was part of the third Service Design webinar. You can rewatch the full webinar for free with all the show notes and slides.