Contingency planning factors into every schedule I create for my daily work life. Whether it's creating a Plan B (C…D…), if certain un-planned risks/uncertainties occur or taking advantage of an opportunity, I make it a point to factor in contingency planning when creating schedules.
The main method I use is the Float Monitoring Technique. As described by Averous (2015), "float monitoring is a very powerful technique that can anticipate with more advance notice future deviations in key deliverables" (p. 248). It provides current state against fixed, or "last reasonable moments." The project manager being familiar with the ebbs and flows of the schedule can expect the float to evolve with the schedule.
Having a solid project schedule template lends well to this technique.
The project schedule template not only identifies critical path, but other tasks that have the potential to become critical. The concept is simple - Watch the float and learn to anticipate when you need to tap into your contingency plan to "magically" get the project back on schedule.
I encourage everyone to practice contingency planning as part of your daily routine. As it does for project managers when we have a back up plan, it gives us peace of mind if the first plan doesn't go well, we've thought through how to pivot. The reality is, we cannot plan for every situation, but we can do our best to think ahead and be prepared should we need to move between plan to contingency plans.
Averous, J., Linares, T., & Project Value Delivery (2015). Advanced scheduling handbook for project managers. Singapore: Fourth Revolution Publishing