Read a thread on another forum where a guy said he ran the numbers on his own course buys and found the only ones worth it were live classes where he could ask questions in real time. That makes sense to me. A recorded video can't answer "but what if my spreadsheet has two tabs," and that back and forth is the whole point. Sounds like you paid for slick marketing, not teaching. Leila Gharani is the real deal by the way, her stuff got me through a job where I had to build reports every week. Maybe stick to free until you find a live class with a good refund policy.

Did the DampRid actually stay dry or just pull moisture from the air?

Doubt the grease is what's saving you. Dielectric grease doesn't conduct, it just keeps moisture and air off the metal, so if your terminals were actually loose or corroded the grease isn't fixing a bad connection, it's hiding it until it bites you later. Six callbacks since March sounds more like you finally started torquing the screws right and stripping the wire clean than anything a $4 tube did. Correlation isn't causation, and the guys who swear by this stuff never seem to have a control group. Show me a before and after with a torque wrench and a meter reading and then we'll talk.