The way boosts spread across the Fedi is also interesting. I once heard somebody say that posts "don't go viral on the Fedi, they go fungal" -- the comparison being to mycelium fibers and mushrooms popping up from them, I guess.
Because you have these overlapping constellations of instances, and so sometimes a boost will bring a post to a new audience.
And that often comes with delays, so there will be these little waves and bursts of activity.