This, again, is a very subjective thing depending on the mesh and your end goal. We’re not saying to never go above this but if you’re continually pumping up the resolution and not seeing the results you’d like you may want to consider tweaking this. If you’re confident you have a good layout you can adjust settings in lightmass to also help with shadows as well. I don’t go any lower than 32 as I’ve not seen a need to. There may be in the future for me to do so. I’ll just leave everything at default settings if I don’t bump it up.
As for the jaggies this is from having a edge that should be straight that is on a angle in the UV. When you read through the WoLD tutorial it will give you some breakdowns for how things work together.
To get the cleanest edge you want to make sure that you setup your lightmap uv to have have all edges on a gridline (snapped). The reason being that anything that falls between a grid point will be marked as a shadow vs receiving light. When you have a straight edge of a corner wall or whatever that is diagonal on the UV it will give you these jaggies.
Give it some tests and see how it turns out. If you’re not sure about something feel free to post here and we’ll work through it together. Once you start to see good results you’ll appreciate your awesome lightmaps! 
@ScrotieFlapWack:
UVs are almost a art form themselves. I have spent more times on some things worrying about my layout than the actual model itself. It gets easier the more you work on it. You’ll pick up on quick tricks that make your workflow that much quicker!
