The reasoning behind my decision to pull at 30 days was the following:
My Gos was very good last year incubating, but I pulled at 21 days and had no results. If you do not have an Egg Buddy to detect fertility, candling is almost useless on Gos eggs. I had two dark ones last year and two dark ones this year.
I think natural incubation is best. Mom knows better than me.
I did not know how my Gos would treat a chick, so I played it safe by pulling.
I have incubated quite a few things and wanted to give it a try in the last stages with a Gos egg.
My Wife wanted to see the hatch and she puts up with all of my birds and is one great assistant.

If you do not have an incubator, then I would suggest getting three of them if you want to attempt the process. One for the last days of incubation with low humidity, one for hatch at high humidity, and one to dry the chick off. Then you need to worry about an open air broader to get them regulating there temperature.