In the Bitcoin economy, time really is money. Every 10 minutes or so, mining machines compete with each other to solve a math problem to win 12.5 Bitcoins, a reward set by the Bitcoin software. The work is akin to trying out billions of combinations of numbers on a safe. The miner who gets the right combination the fastest, unlocks the safe. The more machines you have, the greater your chances of earning coins.
With that in mind, miners try to ensure that every single one of their machines is operating properly, 24 hours a day, seven days a week, 365 days a year. Hence, the most important jobs are in the operations and maintenance department. All day and night, using laptops, miners have to monitor the status of the machines.