熟门熟路

Explanation: Familiar avenue, to understand the situation, a lot of experience. 　　Source: Qing Li Baojia "Bureaucrats" the second time: "Wang Xiaolian is Shumenshulu, tube doors always knew, immediately come in, do not block." 　　Examples: I think - really better than novices. ★ Lu Xun's "Wandering · Blessing"