Yes, it indeed is compulsory to follow a routine. Without a definite routine, you will not synchronize with things and dance with the necessary flow needed to guide you on your journey.
You cannot focus on things and worship them rigorously if you do not do it in a routine. Without a routine, your body will not adapt to the changes and leave you feeling lazy, drowsy, and tired all the time.
Following a routine redefines the way, you do things because it gives a definite pattern to things. Without a specified routine, it will get very difficult to manage time. But, a routine will help you to prepare and revise on time.