In the diary you can record daily how much you use of which drug (NPS, cannabis, alcohol, ..) and at what hour of the day. In this way you get a good overview of your use: at what times of day, during which days of the week or periods of the month.
Keeping the diary up can be confrontational, but it will help you gain insight into yourself. Keeping the diary can play a role in getting more self-control. It is a useful tool for stopping or reducing and taking your life into your own hands.