I want to work the equivalent of 4 days each week and maximize my impact while the time I work is fixed. I have children and I want to spent time with them but

I want to work the equivalent of 4 days each week and maximize my impact while the time I work is fixed. I have children and I want to spent time with them but I decided to stop cruising in my part time job and instead make most of it while not increasing my working hours.