Thervey, welcome to the site.
Like you already noticed it can be sometime confusing even overwhelming how much of certain supplements to take. One source recommends it, the other says it has no positive effects. It would be ideally to intake everything the body needs from food, but like we know that's not always possible.
When it comes to Omega 3, things get even more complicated because it's main natural source- fish- is also a source of heavy metals like mercury.
I am including here a link to a list of low and high mercury containing fish, maybe you will find it useful, if you eat fish:https://www.nrdc.org/stories/smart-seafood-buying-guide