Interesting thread @AmirJamez! I preferably do the 20 minute test of the ramp test, as I believe it gives me a more accurate ballpark of my FTP.
Basically I look at my power duration curve and see what I achieved last time I did the 20 minute test (as a reference point), and also the point where in that 15-20 minute (sometimes it is a little before that) range where my power starts to decline. Assuming I was feeling strong in my workouts leading up to the rest week, I then start my first 5 minute block at that wattage. If I am feeling good, I then try to up the wattage every 5 minutes. This seems to work best for me, and typically results in a pretty accurate assessment of my FTP.