When I was a manager in a big corp, 5% to 30% is spent code reading (basically understanding the machine). Many times together with the team / owner of the comp

When I was a manager in a big corp, 5% to 30% is spent code reading (basically understanding the machine). Many times together with the team / owner of the component. My job was not to do code review - we had a good process in place for that. It was always important to understand what is the internal state of the machine we are building/maintaining. So that I can answer to VP or PM team when they asks "we need to so X".