I don't know about your SRV trip, but mine was extremely productive not only did I find a 4 MM node site, I found 4 of them! All yielding Niobium, Cadmium, Yttrium, Zinc.. Nodes all over the place..
Just prospect brain trees. Use this spreadsheet to find a site with the materials you are looking for, and then make a copy and use the drop down to resort the data so that it lists distances from your target site instead of cubeo. You get 4 guaranteed g5 (g5 or g4 in 2.4, the grade of raw mats in 3.0 mean less than nothing) drops per site, as well as a whole host of other drops. You can read more about it here: https://canonn.science/codex/guardians-trees-brain-trees/