Megaways tumble question

I keep seeing confusion about how the tumble feature works with Megaways slots. When the symbols drop after a win, I get that it’s supposed to give extra chances, but does anyone feel like sometimes the tumble chains just cut short out of nowhere, even when you think a hit is coming? I’ve tried tracking the number of ways remaining during the tumble and it seems kind of streaky - massive wins one session and total duds the next, no in-between.

Is it all just straight variance or is there something sneaky in the math once you get a couple tumbles deep? Wondering if it changes anything about how you all choose stake size or session length when Megaways are playing tight.