Rebel

and 's signature skill, this doubles your progress when decoding rebel bases, effectively saving half the you would have to spend on them for other things.

Since without this skill, it takes around 8-10 to decode each base, this can amount to 2-6  saved every time, for a theoretical maximum of ~42  saved for an unlucky  determined to decode every single base.

The same effect can be acquired by contacting Kivanç/Paola via the Xyloph DB, though, and the bonuses stack (+200% efficiency on decoding). While beneficial, this means that after finding Kivanç/Paola, the Rebel skill is much less important, as it then only saves 0-2 additional every time.

Also, an experienced is likely to skip less worthwhile bases in favour of doing other things (like finding the Xyloph bonus), in which case the skill may only be used on around 4-5 bases, for a mere 4-8  saved all game.

So while useful, it's not so rare to see or  opting for other skills they have.