I was a part of the institute for 2 years and so was my brother, so I have a strong bias towards Vibrant Academy. Well I can only really tell you about the top batches because I was in them and had only interactions with people in them. The teachers are very good, one of the best in fact. But they have a pace of teaching things and you need to be able to keep up with their pace. Many of my friends had this problem and extra effort is required to overcome this. Your workload in 11th is lower compared to the workload of 12th as is in every other institute. In 11th you have 2 classes and 1 classes on alternate days. Whereas in 12th you have 3 classes and 2 classes on alternate days. The institute in general is very demanding of you. You are expected to work hard to achieve your goal. The teachers in particular are very supportive and they will scream at you the moment they find you slacking your studies. One of the professors once said to us that they will be happy if only dedicated students came even if they are only 100 of them and we could get all of them into IIT. If you are dedicated to crack JEE, then they will guarantee your selection in JEE.
In terms of tests, we have a test monthly and they may or may not shuffle the batches on the new rankings. The rankings are cumulative and it’s better if you have a good start in the beginning. They give you a DPP which is a daily practice problem which needs to be done before you come to the next class. There is also a Sheet which contains problems regarding a certain topic and has different levels. There are also some recommended books which are given for homework. All of the material given is discussed in class to clear your doubts. Overall Vibrant Academy is one of the best institute if you are dedicated enough to crack JEE.