I agree the vertical division would be very helpful in visually dividing the large amount of content that you are organizing.
Having just taken a look at the Bluescape Kanban Swimlanes template in comparison to your current workspace layout, my suggestion would be, instead of using lines or a canvas, to use a shape/box as the divider for each quarter.
Then you have the option to Attach notecards to that background box when you want to stay within that time span while remaining flexible to change/move the notecard around. And, of course, when you don’t want the notecard to move around, you can pin it in place.
If you give it a try, please let me know if it works well for what you need.
