Good idea if you're coming back from injury, or looking for an excuse if you get (Fr)Eddied.
The disadvantage being that the cost of not tapering or other errors is probably in the region of 300 places
2 days is ample for a non-target race. I liked to do 1/3rd race distance quite hard on raceday-2, then a fill warmup and some strides on
hmm... that would be enough to make it a non-joke training week. Might do exactly that