Reporting tasks are done no more than monthly. Once the job takes longer, management often moves to quarterly or semi-annually especially if the risks involved in not-knowing are limited.

For many types of information, real-time calculations and dashboarding instead of monthly calculations and powerpointing would be preferable, but the same cultural issues apply. Moving from reporting to dashboarding is disruptive for people and processes. And since big businesses tend to create value for the customer via standardization (up to a point), there is a clear reason for the dislike of disruption too.

There's lots of issues here. One is simply that people don't submit jobs during non-working hours, and most jobs don't take more than 4-8 hours, so unless you have a pile-up of jobs during working hours, the grid tends to sit idle overnight and on weekends. Another problem is that you plan your grid capacity for peak periods (and add a margin for future growth), so it will generally be underutilized. Another issue is that corporations create redundant grids for business continuation purposes, so often you'll have full grids that are hardly utilized at all.