We'll agree to disagree. I've seen some fantastic representations done freehand. Even I get better results that way and I don't consider myself an expert!
As Ian said if you've got splatter or large overspray you need to look at your technique. I can easily spray a pencil line with my
airbrush(es) which is fine for a camouflage demarcation which was originally sprayed freehand.
Many Luftwaffe mottles are quite diffuse,particularly late in the war. This is often complicated by a further overspray,often of highly thinned RLM 02,applied by the units. Fw 190s engaged in low level operations did this a lot for example,but they weren't the only ones. These effects are impossible to replicate except freehand.
How would you do something like this (original war time paint) ?
Except freehand
Any attempt to mask that won't look convincing.
The same applies to this Italian "smoke ring" camouflage.
It's not just axis aircraft either. This is impossible with masks.
How could these have been done with masks?
As I said I don't have any problem with using masks but they will limit the possibilities of just what can be done.
Cheers
Steve