When could your dog "hold it" for a work day?

I know each dog is different so I'm looking for anecdotes. I'm having a really easy time with Brae but I just can't remember what the 'general rule' for adult dogs is. Soro seems to have had iron bowels since forever and he doesn't even seem like he urgently needs to go, even if he's alone for 12 hours during the day.

For Brae, he is almost 10 months old and holds it for about 5-6 hours during the work day. He's done 7 rarely. Overnight, he can easily hold it for 8-9, and I think he did 10 once without any trouble.

It's easy enough to continue this, as my partner works a staggered schedule from mine. And I am not in any rush for him to be able to hold it for an 8-10 hour work day. But eventually, I think 9 hours is the realistic number I am aiming for. Right now, he isn't asking to be let out (can't remember the last time he 'needed' to go). I think it's because we are keeping it easy for him and letting him out before it's urgent, which is my intention.

I'm just curious what others have experienced in terms of your dog's ability to hold it as it matured.