Regarding the check-on-shut-down:
It is an interesting idea, but care should be taken in special cases such as UPS initiated shut-down or low battery laptops - it would be awful to lose power in the middle of a fsck.
Another idea would be to have a time-based forced fsck. This should be beneficial to both people that reboot frequently and bump into the forced fsck more often than necessary, and people with impressive uptimes, for whom the 30 mounts could be years without a fsck.
Regarding the check-on-shut-down:
It is an interesting idea, but care should be taken in special cases such as UPS initiated shut-down or low battery laptops - it would be awful to lose power in the middle of a fsck.
Another idea would be to have a time-based forced fsck. This should be beneficial to both people that reboot frequently and bump into the forced fsck more often than necessary, and people with impressive uptimes, for whom the 30 mounts could be years without a fsck.