As a retired 738 guy, I'm surprised that the bus is so different (no rude answers, please). The 73 autoland flares at 27ft, I think, but Boeing suggest 15ft for manual flares if I recall correctly so 30 seems high to me. I used to try to initiate it between the 20ft callout and the 10 but some effos I flew with did nothing until the 10ft call and managed nice landings. I found that most effos had a useful trait, when I was PF, of cringing if they thought I was leaving it a bit late. I could see this in my peripheral vision and this saved the day on many occasions when I was having a bad day. The very few greasers I managed were pure fluke TBH but I was more concerned about landing in the right place at the correct speed than what the pax or crew thought of my "arrival". I only ever had one hard landing (CAVOK, wind light and variable, broad daylight) and, to this day, have no idea what I did wrong!