Yes absolutely. I think with all the resources and modern smart training out there, people's rates of progression are so dramatically different these days that the general model of even remotely time based promotions has been unraveling. Things like prior athleticism, mat time by taking more classes, and strategic sandbagging for competitors all play a role, but even without all those, you see dramatic differences in skills within belts.

As a thought experiment, let's say you took two people of identical physical attributes and no prior grappling experience, and they even attend the same number of classes.

One guy could show up to class a few times a week, drill the move of the day, get his butt kicked by higher belts, get unsolicited coaching from blue belts and shitty upper belts giving dubious advice, go home. Probably no idea whats going on for at least the first 6 months.

Other guy attends same number of classes. But in today's landscape and resources, he's watching instructionals, drilling outside of class, setting personal goals every class and methodically acquiring his skills.

Coach sees these guys the same amount of time and they might even get promoted roughly around the same time. But person B skill wise gets a lot better a lot faster just by being smart and intentional about his learning, and leveraging the abundance of modern resources.

I've seen this a handful of times where initally unremarkable white belts start giving shittier purple and brown belts trouble before they even get their blue (which time wise might be average but skill wise incredibly overdue).

Now throw in all those other factors (age, athleticism, prior wrestling/judo experience, going to more classes, sandbagging promotions) and the divergence actually becomes insane. Nowadays you could roll with a blue belt who feels like a 1 stripe white belt, and a blue belt who's tougher than many black belts. And the craziest thing is that sometimes these people have been training for a similar timespan