It’s a common way that BJJ is taught. You show up to class, do a warm up, perform unresisted repetitions of several different techniques and then you roll. The warm up and rolling are beneficial, but the technique portion in the middle is ineffective.
Ineffective? Observe the experienced students in gyms that structure their sessions this way. Experienced students spend much of the technique portion talking amongst themselves or don’t bother showing up till it’s time to roll. They’re experienced enough to recognise that this type of training doesn’t improve their BJJ.
K. Anders Ericsson et al., in The Role of Deliberate Practice in the Acquisition of Expert Performance (1993) write on the conditions for optimal learning and improvement of performance.
[…]the design of the task should take into account the preexisting knowledge of the learners so that the task can be correctly understood after a brief period of instruction. The subjects should receive immediate informative feedback and knowledge of results of their performance. The subjects should repeatedly perform the same or similar tasks.
The above describes the technique section of a typical BJJ class, with a single exception. Anders Ericsson et al. further clarify.
In the absence of adequate feedback, efficient learning is impossible and improvement only minimal even for highly motivated subjects. Hence mere repetition of an activity will not automatically lead to improvement in, especially, accuracy of performance.
Adequate feedback. This is the necessary component that is missed by the common approach to BJJ. An instructor walking around telling students to “move your hand one inch to the left”, or “don’t use your thumb to grab” is not adequate feedback. Adequate (and immediate) feedback comes from the resistance your partner gives you as you practise the technique.
If you’re not using progressive resistance in your drilling then your BJJ progress will remain slow and inefficient.