I've now got at least 10 ELWs in every region:
At the start of this trip, I had no ELWs in Temple and was lacking sufficient numbers in Elysian Shore, Vulcan Gate, Errant Marches, Aquila's Halo, Inner Orion-Perseus Conflux, Perseus Arm, The Conduit, Newton's Vault, Izanami and Trojan Belt. So mostly in the western parts of the galaxy which I have tended to neglect.
Found 147 new ELWs and mapped a further 151 of my previous finds. With the LY-R bonus, it netted over 16.5 billion credits and my highest paying system is now 86.8 mil (!). Took me just a month to earn 50% of the exploration credits I had made over the previous 4 years. Madness.