As far as HFT goes, the most common zero seems to be around 35 yards.
If you shot a good UKAHFT spec course with a parallax setting of 35 yards you'd have a hell of a time on the close up targets.
For HFT where you can't range find with the scope's parallax, many people set their parallax such that they can tell the difference between the blur at 40 yards and the blur at 45 yards, this helps with range finding the longer shots. This tend to be between 23-27 yards (although as different scopes have different depths of field at different mags that can vary).
For FT, well you can change your parallax so...
Obviously whilst zeroing you want your parallax setting to be the same as your zero range to reduce parallax error but again as far as HFT goes, once zeroing is done you'd probably don't want your parallax setting to be the same as your zero.