Packing for lightmaps was great in Unity 3. It got a bit worse in Unity 4 (it packed by bounding box instead of tighter packing, but still good). It is horrible in Unity 5 (it fails to pack very simple cases). I am trying to fit everything in one 1k map. So I have this lightmap. Plenty of wasted space I think. I could try bumping up the resolution a bit. So I take it from 42 to 44 and... Did you notice some islands missing? They are in a second lightmap now. Even though the first one still has all that free space. And they definitely fit inside the first. I mean... I haven't seen any other Unity feature regress this much. And I'm including baking with Enlighten vs baking with Beast in that. It has gotten THAT bad. I mean, the logical next step for Unity 2017 is to just not do any packing, and create separate maps for each mesh. Please... Please fix it.