Close range = able to hit by extending arm
Medium range = able to touch weapons, hit arms if they're extended.
Long range = just barely unable to touch weapons.
Out of distance= anything more than that.
In fencing terminology, a feint is a simulation of an offensive or defensive action, so it doesn't actually finish. Feint a stab, finish with moulinet = a compound attack (attack preceded by one or more feints or attacks on the blade). If you finish an attack, but intended from the start for it to blocked and to hit with a second shot, that's called a second intention attack. If you start a stab, intending to finish or moulinet depending on your opponent's response, that's what we usually call an open eyes action. The timing and distance setup is slightly different for all three.
Feints are most effective at the critical point as you are transitioning into close range. From medium range, there's time for multiple feints before a shot hits. From close range, while you're feinting your opponent is probably just hitting you. depending on all the other situational stuff and setup.
There are two levels to combat sports- there's the mental game and the baseline, physical reality. For example, medium and long range feints are totally possible, but they're about setting up the mental situation. It's about choices and setups. But there is also a baseline, physical reality. There is a distance and position at which it is physical not possible to parry. The time it takes the blade to travel to the target is less than the time it takes for the visual stimuli to trigger the reaction and the block to arrive. This is where the idea of "action beats reaction" comes from- action time for the attacker being < reflex + action of the defender. Generally, this is true at close range, depending on various setup factors. It is generally NOT true at medium range- the time it takes to step and cut is greater than the time it takes register the attack and move to block. Somewhere along the line between those two positions is a critical point- the point at which it becomes biologically impossible to start a block. So when I say that feints are most effective, what I mean is that they are closer to that critical point. They are butting right up against that hard, physical reality where it becomes impossible to block. The idea of recovering from a feint is possible with mental-type feints, but not feints at the critical point.
What is usually meant by "high level" is full speed through trained, efficient paths. Any sort of conscious decision process becomes way too slow. You've prepped your brain, your reactions are trained, and once you get in close, you're gonna do what you're gonna do.
If you slow down enough that you can make a decision to finish or not finish, you have to move further away from that critical point. Instead of getting into that hard physical reality, you're playing more of a mental game. That works at all levels from medium distance or further back, but at closer distance, it only works if your opponent is playing too. If they're more of a more pure physical speed mindset, it fails. Feints that change intention depending on the reaction they cause are harder to pull off the faster and more trained the opponent.
When I say that at medium range, there is time for multiple feints, what I mean is that there is, physically, time to do them. There is, physically, moving at top speed, (depending on various other factors, etc) time to do two feints (not "a lot of feints") as you attack from medium distance. and on the other side, the same. during an attack from medium distance, at top speed, there is generally extra time for the defender beyond the stimulus-response and action. So the defender could, for example, feint a counterattack and still be able to parry. Or feint a parry in a different line before closing the one the actual attack is coming on. Or sit and do nothing until they make a parry at the critical point for parries.
The "best" compound attack (using a feint) relies on knowing your opponent will parry and when, and so can be done at full speed. A second intention attack can be done knowing what your opponent will do, but not exactly when, since you don't care if their parry succeeds or not. So those both rely on prediction and not reflexes (on the part of the attacker). An open eyes attack, on the other hand, has a decision point where somewhere along the line you are deciding whether the feint becomes a real attack or if it is going to disengage to another line. Good reading skills matter here, but not prediction - if you could read or predict before you started, it would not be an open eyes attack.
If my feints are indistinguishable from my attacks - right up to the critical point - then you can make the block... 50% of the time. But you're guessing. That's what feints should do- they should FORCE the defender to make a choice without certainty. Whoever is committing before that critical point gives the other person more opportunity to make an informed choice. If I can make my attack so the feint is at the critical point, but after that I could hit three different targets, then my success rate goes up to 66% if we're both picking randomly. If I can make my attack so that I can read your parry and attack the opening line, my success rate goes to %100 if I can get to that situation. Which means the real game changes to the defender not letting that situation start.