We use contexts or tags in task-management because we tend to become overwhelmed with the number of things to do. If one has too many visible tasks to deal with, it is likely s/he will be less productive than trying to take in one or two.
A similar issue can be observed with project portfolios. Trying to juggle several dozens of projects will significantly slow down execution. Sometimes, when I see an organization struggling to eat an especially large “frog” (big & important project), I feel like suggesting:
“Leave just this one thing. And make it happen.”