True -most ovens vary a bit from what the temperature knob says.
Cakes are done when they gently slightly start to pull away from the sides.
If they are doing this[the sides], and the center seems to wobble when you shake the tin -then your cake tins are too thin.
Also -pressing a fingertip on the top of the cake to see how it bounces back, is a fine art. When the cake is firm it is often too well done.
I'm a pro and will just say that you will solve all of these things with practice and with keeping track of your observations.
Then you'll have your cake and be able to eat it.
Oh, if a cake is too dry, then using real whipping cream to frost it improves the cake immensely.
Aloha