This is slightly different to what I'd expect when a bulb has blown as the indicator only sporadically stops illuminating bulbs and ticks really fast. This is different from when a bulb is completely blown and constantly ticks really fast and all bulbs except the blown one still illuminate briefly. This issue only appears on the right indicator, the left one is fine.
As far as written text can describe, it would go tick-tock, tick-tock, tick, tick, tick, tick-tock...
A video may explain much better; https://i.stack.imgur.com/Jyykf.jpg
Due to the inconsistent nature, I've only been able to observe it whilst in the car. From the reflection off another car in front of me, the front bulb definitely did not illuminate during the high-frequency ticking.
How do I diagnose what is causing this? I'd assume it is bulb and/or fuse related?
If the car make/model makes a difference, it is a 2004 Holden Astra.