Gold Skip is a strategy used in Raven Beak's first phase before he is protected by a gold energy shield that prevents him from taking any damage until one of his attacks is countered (ie. his second counter in the first phase).
By mashing beam shots fast enough during the first counter, Raven Beak can enter the second phase immediately without bringing up his energy shield and requiring a second counter.
This strategy saves around 20-30 seconds in the Raven Beak fight.
How to get Raven Beak to do his counter attack fast is detailed in Boss Rush.
Before you counter Raven Beak, make sure to hold down the R button so that storm missiles can be brought into the counter animation. Keep holding R down as you counter him and then wait for storm missiles to charge. You can charge them up to 2 storm locks before the animation ends and phase 1 essentially resets. Once you release the storm missiles, you will need to mash the Y button to spam beam shots as fast as possible to trigger his second phase.
The speed you need to mash depends on how many storm locks you shot.
If you are not very good at mashing, doing 2 storm locks on Raven Beak might be possible. Once you start getting better, doing 1 storm lock on Raven Beak will get easier, allowing you to save a few seconds worth of time. 0 storm locks is not advised as the mashing speed required is very high and extremely difficult to achieve.
This strategy just requires mashing practise, so just make sure you are giving yourself breaks in between attempts so you don't damage your hands. Make sure that you are not hitting B during practice because that will make you jump and cancel the animation for the counter prematurely. Once the animation fully begins, you won't have to worry.
Cuts down a significant amount of time on the Raven Beak fight for any category that fights him.