Recently, I had a new big boss and in our weekly meetings with him, a few of us were caught by surprise at his interest in details. Monthly reports that typically will pass without further questions got queried line by line.
At first, the joke was he had too much time. But after a few months studying him, and noticing his quick grasp of our work, I now know that his method was deliberate.
What I learnt from him was that you only have ONE chance for a first time.
When you step into a new job, there is only one FIRST time you see a paticular report or supervise a particular operation. Especially if you are in a relatively senior position, this is the chance for you to ask the fundamental, basic questions without the risk being seen as stupid or incompetent.
So grasp the first time. Go detail. Line by line, word by word, figure by figure to totally understand the concept.