Theuns the white finish was an aviation paint intended for a semi-permanent, but removable finish. In all the photographs I have seen it covers the camouflage colours beneath very well. It did however seem to wear quickly. I don't have instructions for its removal but instructions for the removal of a similar night camouflage paint state "the total coat must be removed with rubber scrapers...... no work may be done with metal or sharp instruments." Also, helpfully, "work in the direction of the wind if possible to prevent dirt settling on the operator". There is also a suggestion of using petrol on stubborn or oily areas.
I don't think it would have been an easy or popular job to remove these finishes!
I'd say apply a complete covering coat to low traffic areas and show wear/ weathering on high traffic areas,leading edges etc. Remember that the mechanics stood on the spats covering the wheels to access engine panels. That would definitely wear the paint!
Since I am unaware of any directive regarding application of the scheme to units in the field you've got "carte blanche" (literally) to do what you think looks good.
Cheers
Steve
Posting about this paints durability has got me delving! To give an idea of how permanent it was Fw190s of JG 74 removed only selective areas of the white in the spring of 1944 to reveal some of the underlying colours. I presume there must still have been some snow on the ground in March. The white must have been on their aircraft for at least four months by then.
Steve