The idea of going 33 years into the future and 33 years in the past had to do with the methods of time travel, and there are several shown in the show.
"Season 1" Time Travel
The 33 years into the future and 33 years into the past rule seemed to mostly apply for H.G. Tannhaus' time machine, and in a similar way for the Sic Mundus Creatus Est. tunnels in the cave.
The time machine seems to have the ability to travel 33 years into the future and past relative to it's creation in 1986. This means that it can travel 33 between 1952, 1986 and 2019. It's still not completely clear what the limitations and abilities of Tannhaus' time machine are. It does seem to travel freely 33 years in either direction relative to 1986, but perhaps not to times in between the three key periods.
It seems like the Sic Mundus Creatus. Est tunnels we see have a similar functioning, but perhaps for completely different reasons. They too appear to allow free time travel between 1953, 1986 and 2019, without much ability to choose, beyond choosing which of the three periods you are traveling through (left or right tunnel in each case). In the case of the tunnel, there are at least some limitations for how far back those tunnels can ever go, because it is revealed in season 2 that:
the tunnel is not completed by the Sic Munuds Creatus Est. group until 1953. Later in the season, we also see Katharina visit the doors in 2020, but the outcome has not yet been revealed.
"Season 2" Time Travel
In season 2, we start with the fact that it begins in 2052 after Jonas and Older Jonas "The Stranger" touch, and Jonas seems to be taken through time. This already seems to break the rules of the time travel methods we have seen, because it goes out of the 33 year loop focused on 1986; but this is also the first time we have seen a portal opened up in the way Older Jonas did (though it does still follow the 33 rule).
In 2052, Jonas finds a strange orb at the power plant, and using the notes (possible overall S2 spoiler),
Jonas is able to make the orb "stabilize" into the portal that takes him to 1921. This portal appears to be a potentially less primitive form of time travel. It is revealed later in season 2 by Adam that:
that technology is utilized by Sic Mundus Creatus Est. to create a portal in their base that allows Adam to time travel to any time he chooses, without any clear limitations. There may be a range of times he is limited to, but they seem to be far more broad than the "Season 1" methods, and definitely is not limited by the exact 33 year rule as the caves (and most likely the time machine) are. Although much of the time traveling activity still does seem to be focused around the hub years when other time travel is common; it does not seem to be a technical limitation.
It's still really not completely clear how any of this works, but it seems to be fairly self consistent. Knowing that the series ends in Season 3, hopefully we will get some clearer answers on how these things work. As it is with Dark, there could always be a lot more going on than I have noticed here. The level of foreshadowing and small details along with twists make it hard to know for sure if you really understand something until it is clearly revealed (and even then that might be deeper than it looks at first).