OK I'm going to jump in here, let the bombs fly! I have been raising puppies over the past 30 years and mine are potty trained at 8 weeks but need to be watched after they go to their new homes and be taught the new situation, different doors and no outside access. I have had very few that weren't trained at 8 weeks and most have it down by 5-6 weeks.
Mine have indoor access and don't go inside. They will run outside to do their business and come back inside.
They do need reinforcement at their new homes and I tell the people what to look for and how to handle different situations. Mine are trained to use a doggie door on their own and have access at about 4 weeks. I have found they want to go as far away from where they sleep and eat as possible. The outside pen has a top to keep birds out and they will go to the very back of their first yard to do their business.
I always tell people the rule of thumb is - the # of months + 1 is the max number of hours a puppy can hold their bladders until reliably house trained.
I agree that potty training is situational, just as all training is. The rule of thumb on 1hr per month is one I use as well but it's amazing how many think if the puppy sleeps thru the night once or 2x, it's okay, then are surprised when it comes up w/ a UTI.
I've got a "puppy preparation" document that is several pages long now that discusses a lot of this. I send it out along w/ my contract once the pups are ~7-10 days old, so I hope not to have those types of questions anymore unless for some reason they are a late comer to the litter. It's been well worth it as it addresses such things as visitation, diet, training, etc too. Worth a thought.
My puppies are potty trained at 8 weeks and they can hold it for an 8 hours night at 10 weeks. I instruct the new owners to take the puppy out in the middle of the night until the puppy is 10 weeks old and that does it.
"I always tell people the rule of thumb is - the # of months + 1 is the max number of hours a puppy can hold their bladders until reliably house trained.