I hate them. those people that have been in the surveying, distance, know it all business that can just lose one eye or cock their heads o the side and come up with a fairly accurate measure of dimension.
Are they faking it or is it just lots of practice. I’m going to believe that latter.
Practice guessing distances and then measuring.
Know distances of certain objects and comit them to memory as an aid.
Look up on the Internet of there are exercises to do.