Does a Fixed Height Desk help to maintain good posture?

Fixed Desk height cannot maintain good posture mainly because “one size cannot fit all”. 

If the Desk is tailored made for your sitting height, maybe better; however, overall the height of the working desk should allow you to have your forearm parallel to the floor with your elbow at approximately 90-110 degree angle without elevating your shoulder in an awkward and sustained position. Even slight adjustment in height while sitting could enhance your productivity while you perform different types of work task, such as, reading, typing, or writing.