mongodb/mongo-task-generator limits the maximum number of execution tasks which can be generated for a particular Eveergreen task. This is done for good reason because we don't want to exceed the total number of tasks allowed within a particular Evergreen version (50,000 total) and overload Evergreen itself.

const MAX_SUB_TASKS_PER_TASK: usize = 5;

However, limiting the number of execution tasks to 5 also stretches out the patch completion time because it limits how short the runtime of each execution task can be. Ideally we would subdivide tasks for required build variants into units taking somewhere between 12 to 20 minutes each such that the overall makespan is highly likely to be under 45 minutes, even if a task were to time out.