Good advice - it's not just you - I've had problems with sources that I regularly correspond with and stuff still gets "Spammed" - and, as you say, items that that might expect in the Inbox can be in Social, Promotions, or wherever.
Check the Spam every week - that's my advice.
I've had no problems with yours (as far as I know, of course).
A friend of mine got a letter the other day from his electricity supplier asking if they had his correct address - if it was correct, he was to do nothing, but if it was wrong, they asked him to correct it - I don't think they had thought that through....