Here is the good thing about ECF G3 and how that matters for The Finals.
ECF Game 3 was 1 day rest, but it also came when the teams have to change cities. That means even less rest, so it's almost like not even a full day of rest. This would affect players like LeBron the most (high-mileage and older players).
The Finals Game 4 is the only game in the series with just one day of rest. The good thing is that it comes AFTER the day of travel, so that you don't have to worry about flying a plane on your day of rest.
Still, we did not do well in Game 4 of The Finals last year. I'm most worried about this game, even more than Game 1 after the long layoff.