It doesn't really matter.
The Wacom Intuos preferences have an option to keep the tablet proportional or to stretch to fill the available area, use only a single monitor if you have multiple monitors connected, or even to only use a portion of a monitor.
In short, the Intuos preferences are designed to allow you to set things to a work area that is comfortable to you. You don't have to adhere to some locked in setting and learn to live with it.
(Note Babmoo and other tablet preferences from Wacom are generally different and may not offer all the options availble for an Intuos or Cintique tablet.)
I use my Intuos 5 Touch (same as Intuos Pro) across 3 - 27/28" monitors. It works across all 3 and doesn't alter any sense of proportion while drawing. The tablet area is greatly "squished" horizontaly to cover the entire +7,600px width and quite honestly, I've never even thought of your question. It feels perfectly natural to me regardless of where on the tablet I'm drawing.
Truth of the matter is, you will inherently adjust. The same way you tend to inherently adjust when drawing on different sized pieces of paper. And you can tweak as necessary.
Your friend may have had the mapping set up so that he/she was comfortable... that doesn't mean it was a good set up for you. In addition, it generally takes a week or two to get accustomed to the tablet. So just sitting down and trying one for a bit won't really allow you to get familiar with it. It'll give you an idea of how it feels and if you think it may be helpful... but until you use one more often your hand/eye coordination will struggle a bit. I tend to advise new tablet users to put their mouse/trackball/touchpad in a drawer for a week and only use the tablet stylus for everything. After that week, the tablet will generally feel as natural as writing on paper....