So I decided to finally try gnome sequencer. I downloaded it, and went with the standard paladin prot single target script. I removed the abilitys I wanted to trigger on my own.

It now looks like this:

PreMacro=[[
/targetenemy [noharm][dead]
]],
"/cast Avenger's Shield",
"/cast Judgment",
"/cast Hammer of the Righteous",
"/cast Consecration",
"/cast Judgment",
"/cast Hammer of the Righteous",
PostMacro=[[
]],
}

How I would want my script to work, would be like a prioritizer for the abilitys in this order:
1) Avenger's Shield
2) Judgement
3) Consecration
4) Hammer
where the Hammer is the fallback, and should only be used if all the above is on cooldown. However if it would work as simple as that, I get the feeling it would be too much logic, and blizzard would never allow automating things at a level like that.

So I'm guessing that the order of the spells above is not a prio order, but rather an iteration of the abilities in the list, where one is triggered every click? I tried it on a dummy, and it looked more like a cycle of the spells, I even saw the ability on the button change correspondingly, so naturally it often triggered hammer instead of for example avenger's shield.

I made a test for the script above. I simply made 3 of my paladins use the GS, and the other 2 would have the normal abilities. And I just went on with my normal button mashing, where 3 paladins would just use the GS every button click.
Seeing as this works as a rotation, and I'm mashing buttons very quickly, it would mean that hammer would be cast before prioritized abilitys sometimes. At other times, nothing will be cast, when the rotation has reached an ability which is on cooldown.
This was the output on my daily heroic:

Dívinus 20,8% Regular mashing
Diví 20,6% Gnome Sequencer
Ilahi 20.4% Regular mashing
Adivinar 19.8% Gnome Sequencer
Isteni 18.4% Gnome Sequencer

Looking at the output, even if the gnome sequence is not even being used as intented, the dps loss should not be huge. This is probably because my manual rotation handling cannot be done optimal across all characters.
Also in situations where I am stressed (mythics) I can pay even less focus on my rotation. Then using GS would possibly provide a better rotation, and allow full focus on handling encounter mechanics and my other abilities.

But my main question is: Can I write a GS script which could actually work like a prioritizer? Or can I write a rotation script, which would work better than the above?