Each window has all the tabs relating to a specific task.
When you finish a task, you can close the whole window at once.
When you want to pause a task, you can minimise the window.
Your minimised windows show you of your tasks in progress without you having to infer it be checking all of your tabs.
Building the habit is hard, so what I did was install a browser extension that limits the number of tabs you have running, and set the limit to three. This will force you to start using new windows for different tasks. It can be annoying in the long term, but it's enough to break the "new-tab-by-default" habit.