Is ablution considered valid if the skin is very dry and requires rubbing the limbs to ensure water reaches them, with doubts remaining about small areas staying dry after washing the limb three times?

Rubbing (Dalk) is recommended by the majority of scholars, but it may become obligatory if it is known that water will not reach the skin due to its extreme dryness. Nevertheless, one should not overdo it, and excessive pressure and repetition are disliked, as they can lead to delving deep into matters, causing obsessive thoughts (waswasah). It suffices to pass the hand over the limb three times.