I'm not an analog electronics guy, but I heard this on the Internet...
This video by W2AEW: "Basics of Capacitor & Inductor self-resonance, parasitics, etc." does not discuss variable inductances or capacitances, but does cover practical concerns for obtaining a given resonant frequency by selecting values of inductors and capacitors. Roughly summarized, the issue is that components are non-ideal:
They have tolerances: they are not exactly the intended value.
They have parasitics: all wires have resistance, capacitors have a little inductance in their leads, inductors have a little capacitance between their turns, etc. The effects of this increase with frequency.
Therefore, if your designed capacitance or inductance is too small, it will be swamped by the imperfections in the actual circuit.
W2AEW didn't actually say this, but it seems to me that one should therefore choose “balanced” values so that the chosen inductance is large compared to the parasitic inductance, and simultaneously the chosen capacitance is large compared to the parasitic capacitance. I could be wrong there; according to the video there could be and have been whole chapters of books written on the subject. So maybe you want to find one of those.