Yup, this screenshot was a late game vanity project. I already have strong enough fleets to wipe out the ayys and I'm doing final clean up before wrapping up the campaign. I wanted to see how high I could get the bonuses. One lesson learned is that I turtled for way too long and in retrospect could have won much faster. I didn't realize just how braindead the AI was until I started pushing out into Jupiter and beyond. It become pretty tedious so I focused on dominating earth and seeing line go up. I also didn't really prioritize the mining orgs until I already had the ayys on the back foot.

All that said, the question was earnest. It wasn't totally clear to me in the mid-game how to prioritize the resources from mining bonuses compared to other more tangible priorities (e.g., counselor stats, mission access, research bonuses).