Can you please explain how and why with schizophrenia skip out on taking showers sometimes?

Many reasons: People with schizophrenia - or several other mental illnesses - have other things on their minds that can make hygiene seem less important. Awareness of self and others is one of the things that can suffer with this illness. Also, if it is particularly "showers" and other cleanliness matters are ok, it can be a specific delusion or fear. Each case or instance could be different.