First off, congrats to OP on your find!
As for Sapyx's post: yep, that's probabilities for you. The thing is, we only have very rough approximations for what probabilities might be, with many factors not considered. Let's use Chiggy's example earlier, where he said he believes that restricting the search to A8-A9 and F0-F4 gives you around 1 ELW in 35 systems. That ignores that whether a system has multiple stars or it doesn't has a big influence on ELW chances (for obvious reasons), and other factors we can only speculate about so far, like the sector's location in the galaxy, distribution of elements in the system, and even more other things we don't know about, as we don't know how exactly the Stellar Forge works.
But let's suppose that it's true, and on a broader category (like A and F primaries), the hit rate would be 1 ELW in 50 systems. Mind you, probability differs from odds. In this particular scenario, we have 49 non-events and 1 event. From those odds, the probability would be a bit different from 2%, but we can just round it to that for a bit easier calculation. With that, you can play around to see what your chances are of finding more than one ELW in that same set. For example, 1 ELW in 50 systems with 2% probability per system: 37.16% of happening. 2 ELWs in 50 systems with 2% probability per system: 18.6% chance of happening. 3 ELWs in 50 systems, same probability: 6.1%. Or for your example, 5 ELWs in 8 systems with 2% probability per system: less than 0.0001% chance of happening. So you pretty much won big on the lottery there. (Especially if you consider that the probability of a hit there was likely smaller than 2%.) Congratulations!
Do bear in mind that as I said, those are rough approximations of odds and probabilities, so this is not for any sort of precise calculations, just a way to illustrate how probabilities change within a limited number of trials - so, a limited number of systems. For example, if you check a single small subsector only.
You can restrict your search patterns to various systems, but in the end, it all comes down to how many systems you've visited, how much time you've spent searching.
Edit: oh, and consider that EDSM has 28,116 ELWs in 15,337,605 systems. That includes terraformed Earth-likes in inhabited systems though, plus systems that were discovered before journals were added. Also, there's an assumption there that I forgot to clarify: we assume that a system either has an Earth-like planet or it doesn't. Multiple ELWs are not considered.
