Independent instruction could be saying nothing; however, how do you know if your pupil as seen the hazard and understands how to deal with it. You could ask an open question, “What is the next hazard” to see if they have spotted the hazard and then, “How will you deal with it”?
Prompted is reminding your pupil what they should be doing. For example, by saying, “where should be positioning on approach to that roundabout”? or “where should we wait in this meeting situation”?
Guided is telling your pupil directly what they should be doing. For example, “Gently brake to stop”, “look into right blind spot before driving off”?
The level of instruction should in most instances match the ability and experience of the pupil. You should be involving your pupil in the decision-making process as much as possible, to create thinking drivers by asking appropriate questions to match their level of ability. But not to be overwhelming them by a situation they can’t deal with.

With a pupil at the trained level, you should mainly be using independent instruction with prompts, with maybe on occasion guided to prevent a safety critical situation from occurring. Like saying,” Wait” if you pupil is going to emerge out into a path of an approaching vehicle.

With a pupil at the partly trained stage, you should be using independent (if they have mastered a topic of course), prompts (to remind them) and finally guided whenever you pupil can’t handle a specific situation that is beyond their present level of ability.

With a pupil at the beginner level, you would mainly be using guided at first and then to prompt them, with an intention to do something on their own as soon as possible (transfer of responsibility as soon as they are capable of doing so). There are no hard or fast rules when it comes to which level of instruction is needed as this depends on the pupil or the situation, but you really shouldn’t be guiding a pupil at the trained stage all the time or using independent level of instruction with a beginner.
In essence we are trying to prevent safety critical situation from occurring in the first place by using the appropriate level of instruction. Personally, I am not afraid to level the instruction to present a safety situation from occurring.

However, we might not have time to prevent danger, in which dual control use may be required by steering or braking to prevent actual danger.
But we shouldn’t be dual controlling a pupil if they are not going to cause danger or by at high risk of danger. For instance, you pupil is turning right from a single lane into a two-lane dual carriageway, and they are going to turn into the right hand lane but shouldn’t be dual steering them if there is no danger. Or if you pupil rolls back from a parked position on a hill-start with no vehicles behind. If you allow them to roll back, they get experience of the consequences whilst staying safe.