Understanding Smartsheet’s Approach to Float and Critical Path Method

Disclaimer: This article is based on independent research and extensive analysis. While we've made every effort to ensure the accuracy of the information presented here, this article has not been fact-checked or endorsed by Smartsheet. While our research included multiple meetings with the Smartsheet help desk, where we sought to confirm the correctness of our assumptions and gather insights. Despite these efforts, interpretations and explanations in this article are our own and may not fully represent Smartsheet's official methods or practices. As always, we recommend referring directly to Smartsheet's official documentation and support channels for the most accurate and up-to-date information. 

At MustardSeed, we provide project management expertise to clients across the life sciences industry. As a project manager (PM), I rely on the critical path method (CPM) to help my clients – most of whom are juggling an impressive array of projects, tasks, and priorities at any given time – evaluate their portfolios from an objective perspective and achieve maximum efficiency in their day-to-day operations. In the past, CPM was primarily accessible to PMs through complex software programs like Microsoft Project and Primavera; however, in recent years, cloud-based software platforms like Smartsheet, which emphasize ease of use and collaboration, have begun dabbling in more complex project management features like CPM. Today, we’ll explore the use of CPM in Smartsheet. 

Before we get into the specifics, it’s important to define a few terms. The critical path method (CPM) is a project management technique that uses the critical path to plan and control a project. The critical path is the sequence of tasks representing the fastest possible completion of a project; if any task on this path is delayed, the entire project will be delayed. Another key concept within CPM is the idea of float (also sometimes called slack): the amount of time non-critical tasks can be delayed before they join the critical path.  

In Smartsheet, two relatively new functions can assist with PMs looking to explore CPM: Is Critical and Total Float. The former helps PMs identify tasks in their integrated Smartsheet schedules, whereas the latter helps PMs understand the amount of flexibility their teams have to complete tasks not on the schedule’s critical path. In order to make the most of these features, MustardSeed has identified several key assumptions inherent in Smartsheet critical path and float calculations, as well as a few recommended best practices. 

Key Assumptions: 

1.  All schedule tasks need to be linked at the lowest level of the schedule. This is a standard best practice, but one that may be unfamiliar to PMs without a deep scheduling background or experience in tools like MS Project.  

2. Float and critical path calculations are only accurate at the lowest level of the schedule. Let’s say Task 1 has three subtasks – we’ll call them Tasks 1a, 1b, and 1c. In a properly networked schedule, float and critical path calculations will be correct for Tasks 1a, 1b, and 1c. However, the parent row for these tasks, Task 1, cannot be counted on to have accurate float or critical path information.

3. Critical path calculations are sequential. If there are multiple tasks with the same duration and same predecessors in your schedule, only the first of those will be considered on the critical path. Both tasks will still show a float of 0 days, but only one will show up as a task on the schedule’s critical path using Smartsheet’s critical path calculation.  

4. Critical path can only be calculated against the project end date. In some scheduling software platforms, critical path can be calculated against tasks other than the project end date; however, this feature is not yet available in Smartsheet. All float and critical path calculations are in reference to the latest end date present in your project schedule. 

5. Smartsheet cannot handle constraints. Many advanced scheduling programs allow the introduction of task-based constraints to project schedules (e.g., Task 1 must start on June 1st, Task 2 can start no earlier than June 15th, and Task 3 can start no later than July 1st). Smartsheet does not currently have this functionality, which limits more advanced critical path and float calculations (such as negative float calculation).  

Best Practices: 

1. Start with an intentional schedule architecture. With a waterfall project, setting up a clear work breakdown structure (WBS) and mapping out tasks according to the WBS upfront will save you time and energy in the long run. That’s not to say tasks/subtasks won’t be added and removed, dependencies changed, etc. -– it’s about creating a structure for how the schedule is set up and managed. 

2. Create a clear schedule management plan. How often will the PM update the project schedule? If the project scope is relatively fluid, with new tasks or details being added regularly, what will the process be for keeping all dependencies up to date? Weekly updates, at minimum, are recommended for projects with many moving parts, even if it’s just a quick scan. A more holistic schedule review by the PM might be necessary on a monthly or bimonthly basis, to ensure the project schedule remains accurate as the single source of truth for your project.  

3. Make use of the “Children” function. A simple helper column summarizing the number of children below each task in your schedule can easily serve as a workaround for the lack of hierarchy in Smartsheet (though we were excited to see this appears to be on the shortlist of new features to be rolled out in the not-too-distant future!). Any task with a child count of zero is where predecessors should be applied in the schedule. If any task has a child count greater than zero, the predecessor column should be empty. Conditional formatting can help set up highlighting rules to alert a PM to cases where predecessors may be incorrectly applied. 

4.  Make creative use of filters. Completing routine weekly schedule updates, as recommended above, sets the basis for creative use of Smartsheet filters. Some useful filters PMs might consider using for weekly status updates include: (1) incomplete tasks only (hide completed or canceled tasks); (2) upcoming work (any tasks with an end date in the next two weeks that have not yet been marked complete); (3) missing predecessors (any tasks with a child count of 0 and a blank predecessor column); (4) missing owner (any tasks that do not yet have a resource assigned); (5) overdue tasks (tasks with a due date in the past with a % complete less than 100%); (6) Project milestones. These are just a few examples of how creative use of filters can support PMs in efficient schedule management and routine maintenance.  

While Smartsheet critical path management functionality appears to be in a relatively early stage, we have been thrilled to see this renewed focus on elements so critical to project success (pun intended). We look forward to seeing what’s next with Smartsheet’s ever-evolving tools. 

Do you have any best practices you’ve found when it comes to using Smartsheet CPM tools that aren’t mentioned here? Want to talk about obstacles you’re facing? MustardSeed offers one hour of free Smartsheet consultation, and we love to nerd out on project scheduling questions. We’re pretty proud of some of the creative solutions we’ve found in Smartsheet and other scheduling platforms and would love to talk further.