QXC
Rules, what Rules and where does it say any "reasonable ........."?
Simply, the QXC flight flown must be at least 150 nm in total and include two land aways, not including the start and finish aerodrome. No more than that is written or intended.
With regard to navigation techniques. The debate should not be about whether a certain place could be seen on the horizon or not. Such training and qualifying flights should include and demonstrate good technique for use anywhere at any time in good and poor visibilty. I would not allow my students to second guess a fix on the horizon and on arrival at a fix positive ID (3x unique features) must be undertaken. It dosn't matter whether the fix is halfway or part of any other division. How do you know if you are halfway anyway if there are no features. (other than Navaids being employed)
Whatever techniques used and they are numerous, heading, time and progress fixes are the root of navigation. If the wind could be guaranteed to be constant with unlimited visibility then a fix would not be needed. However pinpoints (fixes) are paramount and as BEagle has stated should be obvious and also unique whenever possible. The fix is simply there to assess actual progress in time/track made good so that applied corrections can be made objectively to reach the destination at a known time and within a planned endurance.
One further caveat on which I insist, is that any decision that can be made on the ground before flight, IS! Scrambling around map in hand guess-estimating from point to point is not acceptable.