Time dependence is essentially how much accing a note relies on timing. With a low time dependence swing aimed at the centre of the block, your swing could be a bit early/late and you can still get the 115. The lower the time dependence, the larger the timing windows. You may have seen some people have HitScoreVisualizer configs with small numbers under where the points are shown. These numbers are values from 0-100 showing how much their acc relies on timing, so what does that mean?
Consider a note in one of the 12 positions and an infinite series of notes behind it. Now imagine a line through the centre of every note like this:
If you wanted to get 115 on as many blocks as you could reach, then you’d have to cut down that line. This is what we call a time-independent swing (a value of 0 on the HSV). As a block comes towards you, its centre will move along that line, but since you’re cutting through the whole line, you’ll get 115 regardless of where the block is. In other words, you get 115 regardless of timing.
A practical application of this is dot spam. Imagine the same line of notes, but they’re all dots. If you aim for the first note and hit them “normally” you’ll hit many notes with one swing, and you’ll only be able to cut through the centre of the first. So you’ll get bad accuracy on any of the other notes. If you were to instead swing through the line of centres as mentioned above, you would be able to 115 every note if your aim was good enough.
If you were to swing entirely perpendicular to the line of centres, then your swing would be entirely time-dependent (a value of 100 on the HSV). This means that your accuracy is heavily dependent on your timing and not only that, but the time window to hit the block at all is much smaller.
This can be seen to some extent when “pizzaing” (where you aim your sabers towards each other), you don’t need to aim to hit notes, but it requires more accurate timing than if you were to swing normally. When not used to cheese but to acc, I like to refer to this as windshield wiping. This technique requires a lot of timing, and I wouldn’t recommend it personally, but that doesn’t mean it’s necessarily bad. Players like Taichi and KingRazer are two players that both use a windshield wiping technique to acc. Generally, this would mean that they’d struggle at higher NJS since the timing windows are much smaller for high acc. But interesting enough, I don’t see either of them struggling with it.
Another result of this which many have already realised (especially in true acc), is that it’s easier to move to an outer lane note and swing as if it was the middle lane.
It’s clear why this is easier, you can now swing straight down, and it will be a time-independent swing without any extra angling required. This also explains why accing outer lane, is generally much harder than the middle lanes.
As you would expect, this works the same but rotated for horizontal notes. With normal swings, horizontal notes in the middle row are much easier to acc than in the top or bottom rows. And as with moving over to the outer lane for outer lane down notes, you can crouch and put the hilt in line with the bottom row to make bottom row horizontal timing easier.
If we draw the line of centres for all the different note positions it will look something like this:
The middle two notes were omitted because they would block the others, but the same applies to them. Be aware though that this is drawn from the middle of the grid, your own perspective in-game will be different. To take advantage of this information, you’ll need to get a feel for where these lines are for your perspective. It ultimately just comes down to practice to get the hang of it in-game.
Something else to be aware of is that the note’s direction and colour have no impact on the lines. As a result, there will be many note placements that simply cannot be hit time independently without moving your hands (and potentially yourself) too far to be viable.
HSV measures the time-dependence by taking the z component of the normal to the cut plane. You don’t need to understand what that means or why that works to take advantage of it, but for those that are interested, here’s a proof of it (credit to PulseLane for writing this):
Converted from the original Google Doc by Duh Hello