Invasion stripes will be replicated in the slap dash fashion as seen in these photos.
It needs to be remembered that these were typically designed to be a single use aircraft so I guess finishing was not perfect.
When depicting D-day as well these will have been practically new, maybe an odd training flight and small amount of weathering from sitting around the airfield, but nothing too heavy.
Yes that's what I've found out since researching began. But it didn't occur to me until then.
It also depends on when the model you're depicting is used.
I've read that some of the Horsa's used in Op Market Garden we're recovered airframes from D-day so those would have been significantly more weathered and used.