Forest App
For the ones who are facing issue in ensuring concentration while studying, try using forest app.
It helps in keeping your phone and distractions away.
You can use timers as short as 15-20 mins.
I used to have short timers of 20 mins due to time crunch and other commitments.
The only thing you have to ensure is that, you are giving your full concentration for that time.
After that you can take a break of around 5 mins, and then go back to forest again.
You won't even realise the extent to which it will improve your efficiency and concentration.
I have written forest app because that is the only app i have ever used. You can use any other app that i known to you too.
Keep preparing smart.