I'd say 66 changes sounds a bit high, compared to a couple of known successful routes. It's obviously also due to how you count them.
BTW this is how I count changes/legs (nowadays):
1) If there are through trains (that aren't very uncommon) don't count any possible changes (e.g. going Northern CX Branch to MHE - don't count any changes there. even though it's quite possible you encounter one or two).
2) Count any combination of run/walk/bus/tram/train between stations as ONE change.
3) Count the likeliest route when alternatives exist.
4) Number of legs is one more than number of changes!
With this counting around 50 changes seems like a good target..
Please check out:
http://www.tubechallenge.com/forum/viewtopic.php?t=395