this is my first analog synth and I have a question about the fine tune of my moog sub 37. I wanted to record some leads and the pitch was slightly flat so I fine tuned it with the knob. I had to turn the knob to around 2 o´clock. As far as I understand, this is normal right? Now my question is, why is it that the overall tuning of a synth can vary so much? What factors does it depend on? As far as the practical side of things, do you use a tuner and fine tune every time? Or can I expect everything to stay stable?
Sorry if these question seem obvious to some of you, just trying to understand everything

Thanks!