Automatic Updates Turned Off

I was told by an IT professional to turn off automatic updates because it slows down the network and ties up resources on the clients. In doing so, it speeds up the client’s performance. However, when automatic updates are turned off then the clients don’t get updated unless we manually do them. If the updates do not get applied then the windows defender will not work. If windows defender is not working, spyware attacks the computers. Any advice?