"also i have heard that article students who involve in practical experience take hard time completing final (they cannot concentrate on studies) is that correct "
its a misconception that its hard to complete final when you involve in practical experience, i.e., full time articles.
the first thing you need to understand is Chartered Accountancy is a professional course that merges theoretical knowledge with practical aspects.
your theoretical knowledge helps you to do the practical work and your practical knowledge will help you to understand certain topics in your academic syllabus like standards on auditing, accounting standards and taxation matters which will help you to understand the concept of the topics you need to study. they are inter-related.
once you are a qualified professional, you need to atleast have the idea how to approach to a practical issue and the way to communicate with your clients. you cannot expect to know all at a time. all you need now, is to allocate time to your articles and studies simultaneously. talk to your Principal about the office timings and plan out your study schedule.
you need to remember, there are rankers who have undergone articles and studied simultaneously
ALL THE BEST!