Unless Skoda have changed the Haldex system since the Yeti it is 'on demand'. As far as I am aware. I would be interested to see any info that says it is 90/10. If it has been seen in any motoring press articles, I would take their technical comments with a pinch of salt. They are know to have many incorrect statements.
Haldex has always been an on demand system, but that doesn't mean Skoda haven't changed something. They may, for example, have altered the sytem for Countries that have more snow & or worse roads than we have in the U.K.
The other thing to remember (whoever is correct about the split) is that even if it on on demand there is alway the rear diff , propshaft and output shaft of the Haldex 'bit' that, in 2WD will have to be turned by the rear wheels rather than the the wheels BEING turned. This, therefore, will use more fuel whether it is in 4 or 2 WD.
Skoda have yet to wake up to the fact they have a4X4 Kodiaq. this is for the NEW Octavia. So one can safely assume it is the same in the Kodiaq.Intelligent All-Wheel Drive
With its intelligent four-wheel drive system, the Octavia Estate gives you great stability, safety and traction in all sorts of driving conditions. The drivetrain with a 5th generation electro-hydraulic clutch reacts to just the slightest change under your wheels. In normal conditions, the car is like a regular two-wheel drive car. Let there be snow, rain, mud, and ice and the Octavia Estate's 4x4 ability kicks in automatically.