Is it obligatory to excessively rub, even with fingernails, the dead rough areas and cracks during ablution, which leads to a prolonged ablution and excessive water consumption?

Rubbing (Dalk) during ablution is not obligatory according to the majority of scholars, while the Malikis deem it obligatory. As for cracks in the feet, it is necessary to ensure water reaches inside them. However, exaggerating in removing dead skin and cracks, and spending a long time doing so, is considered from the acts of whisperings (waswasah) and extremism in religion, and therefore should be abandoned.