I'd actually read that as how not to do it to be honest.

Blowing a line with just air will force all the crap inside the line or lodged in the caliper up into the caliper and around the seals and you may begin to suffer severe problems due to this. It is certainly something we would not recommend doing.

Its much better to flush the system with some cheaper same grade fluid Dot 3 Dot 4 or Dot 5.1 or whatever to remove the old spent fluid.

Then switch to the fluid you wish to use and re bleed with that.

That way you never let the lines run dry so the seals in the master cylinder and calipers will not get dislodged by dirt / air thus saving you potential big time grief.

Bleed 1 line at a time so back nearside > front offside and then back o/s front n/s
Keep the calipers not being bled closed.

How do I know if I have flushed enough through when switching to the good stuff...

Note how much you use when you do the initial flush from dirty to clean !!

We use ATE Blue in our competition cars which is a Blue Race Fluid and that way changing the fluid is easy when the colour changes your done !!

Dont worry about the fact you may have 0.1% or whatever of the old fluid in, as its a track car you should be at the least changing it every 12 months or as often as you like during the season.

Link is dead so I can't see what it is you have selected but if you have a Pug which is a light car it will possibly be overspecced as a standard GTi caliper will never EVER be able to dissipate enough heat for it to run a high spec fluid in its confort zone.

Ie there is no point buying a 500 fluid if the caliper will never see temps of over 200 etc You will be changing it often so wet/dry figures are pointless as it should never get "wet"

Tony