There was a time when practice manual was launched for the first time and after that almost for next 4 to 5 attempts majority wuestions asked in exam was copy paste from the practice manual. Result percentage was "high"then as people say around 20 to 25 percent. Most of the students just cleared the exams by reading pm only. So you might have heard its very important, scenario has changed now icai is all geared up to ask really different and difficult questions nov. 14 was an example of this. So please go for detailed studies from good books , have conceptual clarity of everything you study why and how part, what if part everything. Satish m is correct pm is only for checking wether you can apply the knowledge to various questions or not gor boosting your self confidence.