There is a reason that companies give their employees  “vacation” time.  This time is typically earned over weeks and months due to the amount of work that your environment requires. Most people want to make a great first impression when newly hired and they will go above and beyond to prove that they were the “correct” hire.  However, it is important to realize that this company was in business before you and will probably be in business after you. Your skills and ability are valued or you would not have been hired. If you cannot perform at your highest level due to exhaustion and fatigue or burnout, this view can change and will be construed as something other than what it really is. Burnout is not conducive to the stimulation of the mind. Resting and recharging the mind allows for those creative thoughts to take over and allows you to more readily solve problems or formulate solutions. Think about the things around you in life that need space or time to grow and develop. The human body and mind are no different. It is as important to be dedicated and productive in your work product as it is to take time off to rejuvenate and rest. Work-life balance is a critical component to your success.