It is in documentation, because it might be useful way to set the timing,
when you haven't special tools, or the easiest way, but not necessarily the best way always.
But they don't even mention the "special tools"!
The 1.2 8v Punto Mk2 motor is the same engine (in all but bore and stroke) to the 1.1 8v MPI lump fitted to the Seicento.
Now, if you're unfortunate enough to have one of the Brazilian engines, or daft enough to have bought the 1.4 8v with VVT, there's a point. Otherwise, you just use the marks and everything is wonderbarful. I've worked on these lumps for more than 10 years!