Scandisk doesn't -always- occurr after a crash/improper shutdown. I think it only happens when it shuts down when something is writing--perhaps that isn't precisely the case, but I know that ScanDisk isn't always triggered when the system goes down abruptly. Either way, I'm wary of anything that shuts down quickly. I have a number of apps that save their data when shutting down, skipping that would potentially cause me to lose data.
I don't shutdown/reboot frequently enough to warrant such an application anyway.