OK thanks I now see where you are coming from (albeit 9 steps = 1/4 note triplets). However, what you are describing and showing in your video is not really addressing using different time signatures.
What you are addressing is how you can sync different note/rest sub-divisions across multiple tracks by using the combination of pattern length and track tempo scaling, whilst maintaining a common time signature.
Even in a 4/4 time signature, if I wanted to have 1/16 notes in one track and 1/16 note triplets in another I would have to use the same method. (Track 1 - 16 steps - tempo 1/2, Track 2 - 48 steps - tempo 3/2). Obviously due to the 16 step base, 4/4 can be easier because many sub/divisions can be accessed simply by using note length.
When it comes to just the time signature, your choices are one bar per pattern (simpler but inefficient pattern use ) or doing the math to work out the maximum number of bars you can have per pattern and then determining which trigs are on the bar line.
You are indeed correct, pages are not hard wired to bars, unfortunately.
Oh and thanks for the great videos.