Covering past exam papers under exam conditions will definetely help and some will argue is the best way to prepare for most of the ACCA exams.
You will also need to have a good plan to tackle the paper as well. There are 4 professional marks so only 46 to get from the questions.
I always complete my strongest option question first, sticking to the allocated time. I then complete Q1, again to the allocated time.
Laslty I attempt the weaker option question only targetting the marks I know I can achieve. By now I will know if there are more marks on offer in the other two questions I have finished or the last option question. I then spend my last 15 minutes or so revisiting the previous two questiosn or continuing with the last option question. Whichever subject I am most comfortable with.
Generally speaking you will achieve the most marks at the beginning of your answers, therefore I find there is no point spending an additional 30 minutes on Q1 to find you could have got near 25 marks on an options question but ran out of time.
This is how I have tackled the professional papers so far.