The total size 0asw long as it fits my most used rotary mat] isn't as important as being able to go around at least 3 sides - one whole end of the table - for ease of cutting, and then the height that works best for the one doing the cutting.
I love that I can literally move myself instead of the fabric, mat, and all and can cut out patterns easily. Nothing moves but me so I get nice cuts or trims.
ali