How strict are the practical and theory attendance rules of IGNOU?

Whether the attendance rules of IGNOU are strict or not depends on your local centre solely. There is a minimum attendance criterion in place but it differs from programme to programme. 

Once you adopt the habit of self-learning it becomes quite easy. But attending classes will help you clear your doubts once in a while.

The theory sessions in IGNOU are not actual regular classes. They are just sessions to hold discussions between lecturers and students. There is no proper explanation of each chapter, just a general clarification of doubts. Attend these classes only after thoroughly going through the study materials. 

Another benefit of attending classes is meeting new people who will help you understand the topic much better. So if you are a student of IGNOU, the practical and theory attendance rules vary from centre to centre.