Unfortunately for many mechanics it seems to be rocket science.
And how do you know it's required, is you haven't measured it? Usually measurements and adjustment are done at the same time. And i don't think i remember a single case, where no adjustment at all was needed.
Some misalignments might not be felt by most drivers, but some will still feel there's something wrong.
This is one of the things that it's good to do once in a while.
In case of multilink suspension, like in vRS, there's always some adjustment of the rear possible.
Even in case of torsion beam SOME adjustment is possible. E.g. if you hit a pothole, it's possible that whole beam will be misalligned a bit, as mounting points are kind of bean shaped, which means one side can move towards rear of the car. This can be adjusted.
I actually had this case in one of my previous cars (Leon 5F, so basically same rear suspension, as in "lesser" Octavia models).
In some cases, some cars, it's even possible to adjust angles, that manufacturer didn't mean to be adjustable officially. For example, as mentioned before in this thread, by adjusting whole subframe, but also using i.e. eccentric bolts for dumpers etc. Unfortunately there's very few mechanics that know how to do that and even care about proper allignement.