In the hot seat, you are judged by the calls you make. You are rarely an expert on any of areas you make those calls on. Your skills as a leader is to sift through the often contradictory advice you get and make the right call. Also to create the atmosphere when people will give you their honest, considered opinion not just what they think you want to hear.
There is a theory that it doesn’t matter hi many calls you get right or wrong, but that you get the big ones right. The ones that will have most impact. Brown and Darling did during the financial crash. Has Johnson and his government?
I suppose we will judge by the gruesome death toll in relation to other countries. If ours is much higher than countries with a similar demographic and wealth then that will surely reflect badly on the government.