I think that is usually that is due to there being a consecutive series of faces that form a loop that cannot be 'flattened' without some of the faces overlapping others. The unwrapper may leave out a face to enable the rest to successfully unwrap. Remove all the UV map coordinates from the model and try again after hopefully spotting the edge(s) that you should have marked for cut.
I tend to mark the edges I want the UV mapping to cut about as 'hard' rather than UV map the object according to the projection, then scale the various cut pieces and flatten points along x or y on the UV map for easier texturing.
At this stage you can overlap the cut pieces if you wish of course, so for ships which are usually symmetrical you can flip some pieces horizontally/vertically as necessary, centre them all on the UV map, then drag them all to wherever, trying to fill as much of the square space of the texture as possible with your various sections.
That makes sense. I've actually adjusted my methodology now.
I'm setting different sections to different materials so that adjacent faces that would require a cut, don't. Then I'm defining the cuts on the circular bits that I have to and unwrapping.
It's all a learning process for me. The last time I did anything like this in anger was about 14 years ago and the package I had was somewhat basic. I remember trying out wings3d not long after that and it was a little more basic back then and I never got on with it.
Turns out the problems with my mesh were a couple of very small, strangely formed faces that were hidden in a crease that I couldn't see into.
No unwrapping correctly.
Is it possible to use the Virtual mirror, just texture half the model and then mirror it to the other side of the model, or do I have to have the complete model and unwrap that?
I seem to be missing something about emission maps.
I basically took my texture map file and drew over the places I wanted emissions to go thinking if I added it to my config they would be in the same place. This doesn't seem to work.
Do I need to do something different with the model in wings?