There is another problem SV hunters have to solve:
While one shot is still cast, the next one can already begin, as long as there is no GCD that prevent it from casting.
Now we have a very long steady shto cast (1.5 / 1.15 ~ 1.3), only 0.2 seconds slower than the GCD.
Let's assume you click your steady shot just at the moment your auto shot begins to cast...
- = 0.1 seconds
auto shot cast
|---|.......................................|---|
steady shot cast
.....|-----------||-----------||-----------|.....|-----------|
GCD
|-------------||-------------||-------------||-------------|
As you can see, the gcd of the next steady shot will start before the previous cast ends. Because of this, there are long steadyshot rows, just like it happens when your cast is pushed back.
This problem can be helped by using haste or spamming your button less fast (notice, this will result in less dps, too).
p.s.:
The diagramm looks like there would always be 3 steadys inbetween 2 auto shots... This is not correct, because it ignores SpamSpeed (--> slower GCD, ~ 1.525 - 1.6) and latency jitter.