A few weeks ago on the Great Tarmac Rally I butchered a front set of medium Hankook Z221's in a day but was trying to drive too hard, hugging corners too much and understeering. In comparison with dad driving on the Targa High Country the tyres almost still had the labels on them after 3 days! Sure he may not have been driving as hard but we were still giving it a go. A lot of it comes down to the driving style/technique (at least in our case). I just need to work on getting all my braking done before the corner and apex more precisely before powering out. A little more difficult to do rallying compared to on a track but that's what its all about!
Our clutch didn't get any better or worse after the 2nd day. It is a strange problem though, it would slip down low then grip up at higher revs -even during full boost. Made it hard accelerating out of slow corners, especially up Buller! We were just happy to finish!