Need To Sterilise The Pump Parts Every Pump?

Right now I am washing and sterilising the pump parts after every session as my baby is only abt 1 month old and I want to be on the safe side. However as I pump 8-9x a day I can imagine it will get very hard to keep it up along with having to care for baby on my own soon. Isit necessary to sterilise after each wash or just wash after each session? Read about put pump parts in fridge until next session. Is it safe?