Junctions are frequently harder to negotiate than they seem from the passenger seat. The learner driver will approach at a moderate speed, see several things going on at once, and then simply blank. That blankness is rarely down to one glaring fault. It is more likely to be the result of trying to assess speed, distance, signs, steering, braking and timing all at once. The remedy is not to just push them to be bolder. The remedy is to reduce the number of events that are happening at once and make the approach more structured.
The first piece of structuring should happen before the junction is even reached. Rather than driving up to it and praying that the right thing to do becomes obvious, begin to read the junction from a distance. Spot the sign, check your position, lift off and prepare your feet before you even reach the limit line. This helps because sudden arrivals create hasty judgments. If the car rushes the give-way line then the eyes dart, the hands cling and the gap the driver is trying to assess feels smaller than it is. A more leisurely approach allows the driver to structure their observations into a sensible order rather than grabbing bits of information in the nick of time.
One very useful exercise for the learner driver is to practice the same junction over and over during quiet periods rather than facing lots of new ones. Drive up to the same junction and focus on one question during each attempt. On one attempt focus on how early you can spot the junction and begin slowing for it. On the next focus on where you stop and whether you have a clear view. On a third attempt focus on whether you are looking in a steady rhythm or just darting your eyes in desperation. Repetition on the same junction helps because the junction itself becomes less novel, leaving more capacity to focus on timing and observation.
One particularly common fault is to fixate on the nearest approaching car and to treat that as the entire problem. This usually leads to hesitation and then a clumsy manoeuvre. Good junctions are about reading the overall situation. The driver needs to focus not just on the closest car but the overall speed of traffic, the position of the next car and whether the intended route will be clear by the time the driver reaches it. If the driver finds themselves fixating on one car then force the eyes to broaden their focus. Let them sweep across the whole scene and then back to the point of greatest danger. That broader focus usually makes the decision less frenetic.
A short practice session might be fifteen or twenty minutes of repetitive practice. The first few minutes are spent driving to a suitable junction and approaching it at a speed that allows the driver to feel settled before each stop. The middle minutes are spent repeating that approach over and over, even if that means turning round and driving back to the same junction rather than driving on and facing new ones. Each attempt should focus on one thing, such as: stopping smoothly; judging a gap without rushing; moving off smoothly once the decision is made. The final minutes are spent driving away from the junction on an easy road and thinking about one action that felt more fluent than before. That final act of reflection helps the driver to notice progress.
If they are really struggling then do not force them to attempt the full manoeuvre at full speed. Break it down. They can practice approaching and stopping without actually turning. They can sit at the line a little longer to study the traffic rather than trying to grab a gap that they are not sure about. They can even practice the full sequence quietly to themselves before reaching the junction: slow, look, stop (if necessary), scan, decide, go. Learning to negotiate junctions is about making timing less mysterious and that will only happen when the approach has been practiced enough to give each decision time to form.