Yes that's right. It I recall, back in the day you could do around 8 turns in a single one if you got the right combination of tiles. Since then, and especially recently, there were a lot of extra turn mechanics added, making the potential that much greater. And all of the new additions are true extra turns, not the pseudo ones from builder or bazaar.
It would be interesting to calculate the maximum possible turns one can condense into a single turn.
And that is why I started this thread.
What if you are using the Saint Nicholas Scoreboard, you have 4 points and the other 3 players are all between 10 and 20 points. You place a tile on your builder’s feature which is already fairly large. On your builder second turn, you place a 20th anniversary extra turn tile to complete the builder’s feature which give you 26 points. You are the last to pass 6 points and the first to pass 24 points, 2 extra turns, plus the 20th extra turn. Using these 3 turns, you place your builder on another feature on one extra turn and score another builder second turn on another extra turn. This could go on and on and on.
We are considering a house rule that you can only take each extra turn only one time per turn. Extra turn tiles can create additional extra turns, but not if you have already taken that extra turn already on this turn! But, yes, Saint Nicholas does have two different extra turns!