I’d say it’s the lightmap uvs…
If you want to use lower resolution lightmaps then yes you should keep more space between the islands!
What I would do in this case is keep the whole pole together (now it’s in 3 pieces). The metal part is almost good except the flat parts have their cuts in a wrong place! I would select one side and have a flat map! Like this it would keep it together and wouldn’t have those seams…