Comprehension is the descriptor most often trained by accident and least often trained on purpose. Here is a routine that takes twenty minutes, three times a week.
Start with a busy approach frequency at a large international airport. Listen for five minutes without trying to understand everything - the goal is only to hear the rhythm and to pick out callsigns.
Next, take one exchange and replay it until you can write it down word for word. This is uncomfortable and it is where the gains are. If you cannot get a word after four attempts, move on and come back the next day.
Then change the accent deliberately. If you fly in Europe, listen to somewhere in South America or South East Asia. Unfamiliar accents are explicitly part of the ICAO comprehension descriptor, and familiarity is the whole skill.
Finally, spend five minutes speaking. Take one exchange you transcribed and say both sides of it out loud. Listening and speaking are not separate skills at operational speed.
Bring the transcriptions you could not finish to your next lesson. The words you cannot hear are more useful to a teacher than the words you can.
