Time-on-task

Time-on-task is the time spent practising a particular task, such as speaking a foreign language.

Of all the factors that affect language learning, time on task is probably the most important. The longer one spends learning a second language, the more likely one is to have success at learning that language. Advertising for language courses often make dubious claims that their method leads to results with less effort.

This is a concept that is fundamentally important in course design, lesson design, etc.

It’s why backwash from testing is important. It’s also why ESP exists. And if you don't follow it, it’s likely to result in negative student affect.