This week I drank Rioja and reviewed Nozbe. Undoubtedly the former was more pleasurable but the latter resulted in me stumbling upon a highly contentious issue among productivity minded folk. Indeed, it confronts anyone compiling a task list or managing tasks in a business environment. As indicated by the deceptively harmonious title, this is the first part of a three part series whereby I address the pros and cons of nested and flat task lists.

One of the Nozbe design decisions was to restrict the depth of the task nesting. So, you can have projects, task lists within those projects and checklists for each task. One cannot have sub projects, subtasks etc. Nozbe is not alone in this regard. Others such as Wunderlist and TickTick are similar. Some people would prefer to have a task hierarchy or a greater degree of task nesting to allow for “filing”, tasks or breaking them down into smaller, more digestible chunks. All of this got me to thinking about what advantages and disadvantages task nesting provides. In this article I will cover the pros and cons of nested and flat task lists. In the follow up article, I will show how to get the best of both worlds with a practical example. So, let’s start with the pros and cons.

Hierarchical task lists – Advantages

  1. Provides context and enables task brevity.

    Each level of a nested task provides the background or context to the underlying tasks which means the task itself need not be described in detail

    This is an often overlooked point but in my opinion, an important one. Each level of a nested task provides the background or context to the underlying tasks which means the task itself need not be described in detail. Referring to the example below. For the actionable tasks – measure quantities, mix and pour, they mean nothing without the background or context. But, referring to the parent tasks immediately indicates that. So, not only is the context provided but also the task entry itself is the epitome of brevity. If this were a flat list, we would have something like, “measure the quantities for the cement consistently for the house foundations”, “mix the cement for the house foundations”. Etc. These long statements take time to write. Given that entering tasks tends to be a manual process this additional time directly adds to the time required for managing the list.

Build house

Build foundation

Mix cement

Measure quantities



  1. Natural way to break down complex projects. Task hierarchies are often the most natural way for us to break down complex projects into actionable tasks, whether that be Work Breakdown Structure, Gantt charts or even mindmaps.
  2. Systematic and navigable task browsing. From paper files in a filing cabinet to the windows folder structure to companies and organizations, hierarchies are something we are accustomed to working with. For tasks, a hierarchy provides a systematic filing system. This is especially important for teams which may share tasks. Team members need to be able to browse and find the tasks relevant for them. Granted that filtering and search functions can assist if the search/filter terms are known, but for browsing, systematic filing is still useful.
  3. Hierarchies are the universal language for task management. If you seek to import or export tasks from other media such as mindmaps or Gantt charts, then a nested task list will be the result.
  4. Avoidance of information overload. Hierarchies or outline views tend to be collapsible so all superfluous branches can be collapsed, concealing the tasks that are not of interest.
  5. Follow up tasks can be logically placed. If your work is like mine where doing one task leads to several follow up tasks, hierarchical structures seem the logical solution. These follow up activities are simply created as child tasks.
  6. Scalability. Hierarchical task lists scale reasonably well both in terms of the number of levels and the number of top level parent tasks. Even with large numbers of tasks, the structure can be perused relatively efficiently without significant time penalty.

Hierarchical task lists – Disadvantages

  1. Navigation time when adding new tasks. Since hierarchical lists mirror legacy filing schemes, tasks should be “filed”, in the appropriate place. Often this involved browsing through the hierarchy and adding a new task under the appropriate project. This can take time when doing it for every task.
  2. Superfluous context and depth of nested tasks. Most of the time people are most interested in the actionable task and perhaps one or two levels above that to understand the context. Levels above that only add to the navigation time to the actionable tasks and after viewing those tasks once to understand the top level goals, they are not of further benefit to executing the bottom level actionable tasks.

Flat task list – Advantages

  1. Actionable tasks one click away. Since there are only projects and task lists under those projects, it requires but one click on the project to view the constituent tasks in the underlying task lists.
  2. Conducive to mobile productivity. Mobile platforms such as mobile phones and tablets normally have scrolling for navigation. This one directional navigation suits a one directional task list as opposed to two directional nested lists.
  3. Quick “filing of tasks”. With flat task lists, we do not rely on a hierarchy to file the incoming tasks. Tasks are put in a single task list which can be done at the point of task entry. No browsing through hierarchies is necessary. These days, tags or labels are also popular as a second mechanism for task organization. Again, a quick hashtag can be done at the point of task entry.

Flat task list – Disadvantages

  1. Longer task descriptions necessary. As described in detail under the hierarchical advantage #1, upper levels in a hierarchical task list provide some context to underlying tasks which negate the need for long task descriptions. Flat task lists need more description to explain, therefore longer time to enter.
  2. Inordinately long project, task and tag lists. Hierarchical task lists expand in two dimensions and can be collapsed. Flat lists only extend in one direction which can lead to a fair amount of scrolling. If tags are used, they also multiply over time as the historic tags also need to be maintained to enable searching of completed tasks.


So, that’s the first part of this article on hierarchical and flat task lists where the advantages and disadvantages of both approaches have been described. In the next weeks I will publish further articles covering the application of nested and flat lists and how one can yolk the benefits of both kinds of lists with a single app. Don’t forget to drop by for those or alternatively feel free to subscribe to get them automatically by email. Finally, the shot below shows my current tipple. I heard some interesting tips this week about wine. First, how to judge how the body of the wine. Holding your hand behind the glass, if you cannot make out your fingernails it is full bodied. The second useful tip was that if you count more than five fingers, stop drinking!