Not for ALL of them, so no I thought we agreed that Harry could NOT use LC unless a tracking spell would have worked. He doesn't run home and use LC at all times. He uses it with convenience or when he wants more out of a tracking spell other than a triangulation. Remember when he tracked Thomas in WN?
The car analogy is this. If a tracking spell will not work, then neither will LC. He can do whatever he wants and LC sits there dead as a lump. The moment a tracking spell WILL work then LC will do things. So why would Harry use it if he had already tried tracking and it didn't work?
So, let me repeat...if a tracking spell that does not use LC would not track a target then LC does nothing. You can do whatever you want to LC at that point and it is just a model sitting on a desk. What LC does is allow the tracking spells to do more in Chicago than just triangulate. The reason that LC is not useful in finding Thomas without a tracking spell is quite obvious...you would still have to cover every square inch of Chicago and then you still might not find him (because he would not be in Chicago).
If Harry felt it was worth trying a tracking spell, succeed or not, and he was home, he'd go straight for LC in a situation like that. The more he knew about the location where Shaggy was holding Thomas, the better chance Harry had to rescue him.
Using a regular tracking spell, assuming it works, means he might find himself in a dangerous place with no idea of what lie in wait for him.
The issue is not if the tracking spell would work or not, the issue is that if Harry was home and was going to try an tracking spell anyway, he'd use his best tool to do so, LC.