High risk = High gain. Majority (my guess 80%) gets built but minority (especially new developer that comes out of the blue) gets stuck at site fencing stage for a few years before the developers abscond with the deposits. So far all landed projects that I have come across for the past 2 years are mostly in the midst of construction or have already VP.
depends when also. now when market is rising and lots of hot money coming in, chance of abandoned project is reduced a lot. if during recession time, be careful!