Every planet needs a mix of production and other buildings to maximize output, this I get. However, if you wish to construct buildings quickly, then you need a lot of factories, which leaves you with no room for anything else. If you want to build quickly, you can research but that would require research buildings which would take forever to build since there are no factories (or few). And why is it that manufacturing points are local whereas research points from all planets are pooled? Have I missed anything? What am I supposed to do with planets like Mars that have 3 or 4 vacant tiles?