Here is a trick for handling IELTS gap-fill listening questions.
The IELTS listening paper has four parts, and the opening and closing sections are always gap-fill. That makes this question type worth getting right. Each type needs a different skill, depending on what it is actually testing.
What are you listening for?
Think about it: for gap-fill, do you need to understand everything the speaker says, or just skim for the general idea?
Neither, as it turns out. The gaps are specific pieces of information: somebody's name, address, age, occupation. So this is listening for a particular set of facts. The academic term for it is listening for specific information.
Think about how a waiter listens
Do they try to take in everything, whether the customer is cheerful or fed up, what they make of the restaurant? Or do they care about what is being ordered and whether there are any special requests?
A good waiter obviously listens to the customer. But if they absorbed every word from a hundred customers a day, they would be exhausted.
Go a level deeper. The listening starts before she even reaches the table. She already knows what she needs: starter, main, drinks, how many people, any allergies. When the order comes, she locks onto those items, probably writing them down, and lets everything else wash past.
The interesting part is that she may not process full sentences at all. Keywords are enough: "pho bo", "latte", "no chilli", "extra crackers". That completes the job.
Gap-fill listening works exactly the same way. Know in advance what kind of information you need, then wait for precisely that.