Well, it is still indicative. Many people who fly business are "elites" who get free seating. So in my case there were 30 seats available before seating assignments started. But the flight was C4Y4 due to being heavily oversold in Go. If you go by the C4 number then you will also be misled into making a high bid; with only 4 seats the min bid would be higher. I was awarded 4 seats 28 minutes before the 24 hour mark based on my "weak" bid of $417 with $350 min. At T-18 hours t the seatmap showed 18 free seats. So 8 other seats represented a combination of other upgrade bidders who won and non-elites who did not buy seats. My experience is that you are assigned a seat at T-30 if one is available. When I checked the seatmap, seats had been assigned. I know people on this flight who got op-upgraded (Diamond status) from Go.