Pro tip: If you buy a clutch from us, we make sure you get the appropriate length slave cylinder to match it.
The hydraulic slave cylinders are self adjusting. The throw out bearing is only pushed back as far as the clutch fingers push it back, therefor it is always right at the fingers with no air gap, so no need to readjust for clutch disc wear and pressure plate finger movement. The clutch pedal should never have to travel more than 3-4" to release/open the clutch (depends on master cylinder bore size).
The only time these can be an issue is if you do not run a clutch pedal stop and over extend the piston and pop it out of the housing, which requires one to pull the engine to pop the slave back together. Or if it over extends into the pressure plate and causes fingers to contact the disc. (This can also happen with VW type arm and external slave cylinder for what it's worth)