Tom is the expert, but...
I think you have to consider your drainage to answer that question. If your soil drains well, you can water a sago about all you want and not hurt it. If the soil doesn't drain, you need to be more careful.
If your soil is wet on the surface, your sago doesn't need more water, but even if it isn't wet on the surface, you still need to know how well water is draining away below.