How to handle long lists
Review old tasks
If you've had a task in a list for months and did not touch it, consider deleting it. You should not put everything you can possibly think of in Lunatask just because it might be useful in the future. Does it still make sense to track it? Remember, if something is important, it will come back one way or another.
Review your tasks (possibly using the built-in Priority List or Eisenhower matrix workflows) and remove what's no longer needed or relevant.
Perhaps something can be delegated to other people and moved to Waiting? Alternatively, you can create a separate list (either using an areas or goal), call it "Icebox", and then put these tasks there, so they don't clutter you main task list.
Give it structure
If you still have 80 relevant tasks in your Later section, then you have 80 tasks in your backlog – there's no way around it, and that's okay. The important part is using various sections and priorities cleverly to you know what is first, what is after that, and what is later.
In Lunatask, it's up to you to give Now and Next sections (your current focus) their meaning. Try playing with what the Now status means to you to reduce the number of tasks in there. Having 80 tasks in the backlog is okay, whereas having 80 tasks to work on Now is not. By planning only a small number of tasks at a time, you can give a solid structure to your long task list, and can actually focus on what's important, meaningful now in a manageable way.
Plus, given that your Later section is always by age and priority as well, there's already some structure in it by default.
Hide what's not actionable
After you review and clean up your task list, don't forget to hide tasks that are not actionable at the moment out of sight. In Lunatask, you rarely want to have all tasks in the list shown at the same time unless you're in the process of reviewing and cleaning up your task list.
To do this, simply click the names of Waiting or Later sections to collapse them
In the "Next to work on" overview, you can collapse certain areas the same way. Additionally, you can hide an area completely from showing up in the "Next to work on" overview in area setting.
Using goals to hide tasks until their time comes
The ability to change their tasks' visibility is a great feature of goals. In the goal settings, you can switch between showing all tasks or just actionable ones belonging to the goal in the main list of tasks for the area. You can use this to hide tasks belonging to future projects or create lists to hold not yet fully fleshed out ideas without creating a separate area for them.
To give an example, we might create a goal named Backlog in our area dedicated for work-related tasks. Then, we switch the goal's "show in area tasks" option from all tasks to only actionable tasks. Now, all tasks marked as Later belonging to this goal won't show up anywhere else in Lunatask.