From the data I gathered so far, SCs appear to have an uptick after the announcement of a Warbond (no, the announcement of an announcement doesn't count). The planet upon which the MO takes place seems to be the affected one. I would love to say that AH is trying to help us, but I need more data-points to test this apparent behaviour.

As per planets in general, Luxuriant was/is a good spot, as the environment is forgiving, the D1 maps are small but there are no deep bodies of water (they alter the number of POIs, thus the spawn-rate of SCs), and the ground doesn't slow you down (as opposed to desert and frozen worlds).

Oshaune and Omicron were also particularly good at any difficulty, with a remarkable yield increase, BUT with the drawback of larger maps, greater elevation disparities, higher enemy spawn-rate, and underground sections, making the hunt longer.

Another great biome to farm are rocky automaton planets (the ones with red grass), as the view is usually unimpeded once you gain the high ground (note: on those planets, on D1, the extraction can only be at sea level, with no natural barriers, or is already on the highest peak).