You can use 'rains and rains' to express that something is annoying you and you want it to change or that you are impressed by how much it happens. It rains and rains during the tropical storm Similarly 'runs and runs' the football player runs and runs through the whole match, he has lots of energy. The politician talks and talks and never let's anyone else say anything The baby sleeps and sleeps, he must be exhausted. He jumps and jumps all day, he loves that trampoline.
Avrei tradotto più con un Piove a catinelle. È un'espressione più sensata.