I see it as a purely precautionary safety measure, since there's no other way to ascertain what's at the other end of a jump besides sending something ahead to check. As workable as this method might theoretically be, I don't expect a ship to be able to calibrate its jump with much exactitude other than direction... distance will largely be a fine but educated guess, and a ship might have to make a number of jumps to minimize the distance from arrival point to final destination. Better to let a probe do all that multiple-jumping to refine the distance calculation. It may not encounter anything after 1,000 jumps... but the one time it does could be disastrous, much like the one time in 5,000 flights that a plane crashes... overall, a simple check that's worth the trouble. I suppose some less cautions ships might skip it... and every once in awhile, a ship wouldn't turn up at its intended destination when it dropped too close to a gravity well, a source of lethal radiation or (the silliest trope of all) the miscellaneous asteroid field.