I use Kanban with manually created cards based on preexisting notes, with the Dataview plugin to get the tasks from the respective note, so that within the Kanban view i can see the subtasks required.
Alternatively i also have a view of all tasks accros notes ( grouped by custom metadata).
In terms of workflow, i start my morning by looking at the Kanban and tasks view, and calendar/Slack/email, after which i plan my day with the Day Planner plugin ( which is kind of abandoned and not really necessary besides an automatic Gantt view of the day, and an indicator of where you are on the current thing and how much time remains until the next one).
Sorry. I saw this a little late. Hope this reaches you. I just make use of normal files and backlinks. No fancy whizzbangs except for a script to run the tickler for me. I need to convert this into an Obsidian plugin at some point.
The folder structure is simple
root folder -> Inbox.md (everything goes there first. I have shortcuts on mobile to open inbox directly)
Sub folders for Projects, Tickler, Attachments, Next Actions, Tickler, Someday Maybe Lists, and References
Attachments is just the folder that Obsidian automatically attaches stuff into when I paste/drag'n'drop something in.
I have about 9 Next Action lists inside the Next Actions folder (broken down by type of work [personal, work communication, work tasks, self education, etc])
Every project gets its own file inside the project folder. This will have links to sub projects and will also have its own notes and updates about the project so that it becomes a one stop location to check on a project and its history. When I finish/halt a project I move it into the Completed or Discontinued sub folder in the Projects folder.
When I need a next action on a project, I open one of the next action lists and use and add a task in there with a backlink to the relevant project. This way when I am reviewing my projects I can use the backlinks panel to see what next actions I have pending.
References are additional things like mails/announcement I am writing up. I insert references to these inside the project document (I'll use ![[project X status update announcement]] to embed)
The tickler is exactly like it's described in the book. Each day and each month gets its own file. I came up with an alphabetical arrangement method so that it displays exactly as the book specifies it — days coming up, next month, the days of the month that are done, the months that are coming up, the months that have completed (in that order). Re arranging this requires a bit of precise naming of files which is why I have a script to do that for me. I run `tickle` when I turn on my computer and the tickled tasks go into my Inbox.md file and everything is arranged automatically.
When I need to pick a next action to work on, I have several workspaces I have saved (eg: Work tasks to choose from). I open the workspace, review a next action to work off of and get into it.
And that's all there is to it. It's a lot of words to describe a process that doesn't require any mental overhead to maintain. The only mental overhead is in following the process required by GTD and that's a given :D .