Notice:
The following may not represent the views of a PBW master.
1) I don't take advanced storage too often these days, but my colonies' research is typically all-or-nothing.
If its not worth a resource extractor on the first facility, it won't be worth it on the Last facility unless the planet was of borderline value and there is a major disaster such as a nova in a resource-heavy system.
If your empire is small enough that you have to consider mixed-use worlds, you've got bigger things to worry about
.
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2) I typically use one or two SY per system, stacked with low-maintenance BSY, so no. Parallel production, and massive centralized repair and resupply services. Always with a healthy pile of defenses and ships, of course.
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3) Why not! Losing research is better than losing the
production which is maintaining your defense fleet.
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4) See above
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5) Resource storage is overrated IMO.
If you're wasting resources, you simply need to build more stuff.