The majority of the moment clocks are simply not that large. Hands and pendulums are short as well as lightweight sufficient to get lots of torque from the smaller AA cell. Nonetheless, also in this situation you could wish to opt for a C battery if the clock is fairly inaccessible and also you wish to minimize battery changes.
Building grandfather clocks, mantle clocks, or various other timepieces including pendulums can be rather rewarding. As well as unless you are supersizing your items we recommend using tiny AA battery pendulum clock movements.