I assume you mean polylines.
At my last job I designed parts to be laser cut.
In order to get continuouse smooth tool path we had to polyline(I assume thats what you mean) the tool path.
The geometry was made up of arcs, lines etc but when polylined it is viewed as on continuous entity.
If we failed to polyline it would do as you said or worse. It looked at each entity as small subpaths so ti might cut an arc in one place and then shoot 3 feet away and cut a different segment and basically keep skipping around. The whole part would cut but extremely inefficiently and with poor quality as it woule leave a mark on th pierce and exit of eac cut. Consider endpoint bieng coincident and these marks amplify.
Another good thing to to is create your own lead ins and outs in your geometry and not leave it up to the software. For instance if I were to make a 4" x 4" square I would make one corner my desigmnated lead in lead out and extend the edges there so that my pierce and lead out was off the desired finished geometry. (see pic)
I have never used a plasma but I assume some of the things I mentioned are
common to all tool path generation