Avatar was definitely highly hyped up years before release. Its OW was actually diluted because of a major snowstorm. There was a ton of focus on what Cameron as doing next after Titanic. TFA still had great legs for a holiday release, so I fail to see your point there. And for I2, it's pretty much the same case as TA in that regards, there's been a vocal base screaming for a sequel, but I reckon a good portion didn't care until they knew it was happening.
Hell, Infinity War right now is having much better legs than most of us had predicted, some of the best legs out of MCU releases, and that movie was 10 years of build up.
If there was major frontloading then we should see it within its internal multiplier, like you would in a Star Wars film, not necessarily its external one. External multipliers are almost always determined by a mixture of genre, competition and reception. All three of those things work in I2's favor when it comes to legs.
It sounds more like you're trying to talk yourself into I2 being close to whatever your original predict was.