Unless you have found yourself working with a very peculiar group of people, you are being duped or just exaggerating to the point of being outright wrong.
It is absolutely not a custom anywhere in Brazil, not even in Rio, to be late (_at all_) for professional appointments.
_Especially_ systematically late that a "system" like that is put in place (and supposedly works). To be blunt, the idea that you could correct such behavior from professional adults by duping them with altered schedules is even childish.
If this is indeed the case, please post the name of the company so we can blacklist everyone that works in that office
My observation, being born and having lived in Brazil for my whole life, is that there's a power/authority/seniority dynamic involved, too: If you have a meeting with a customer, you should be on time, but it's okay for them to be late. When meeting with your boss, they'll probably be late, but you probably shouldn't be. Internal meetings within the company usually start later than meetings with other companies. Once you know people professionally for a longer time, you'll also be more comfortable arriving later.
My Mexican friend traveled a lot here for work to meet with various executives. These executives would be the ones who set the time.
She'd drive four hours and arrive at their office for a 8am 1-on-1 meeting and be directed to a sofa outside their room. She told me often 30+ minutes would pass and the guy would be in there twiddling on his smartphone, she could see him right through the blinds.
It was like some proof of time-burn to remind you that they had the power.
I live in Minas Gerais, where things are not this bad, but last month we gave a party for my daughter's birthday. All the invitations were sent with a 30 minute offset from the real start time as agreed with the caterer because we knew everyone would be late, and it turned out fine.
All my professional meetings start at least 15 minutes late, and it enrages me to no end! Yes, it is really that bad!
>To be blunt, the idea that you could correct such behavior from professional adults by duping them with altered schedules is even childish.
I tell you, it's real...
In Los Angeles it's also about -30 to -60 due to traffic, fire or both.
You have to tweak it a bit for different situations (for example, a meeting, is about -15, a conference call, -10, but an after work event is roughly -30 to -60, but works well.