Actually, no thats not situational. That will happen EVERY SINGLE TIME you attempt to use a Custap Berry on a Reversal set. I guess if you eliminated every single priority user or scarfer on your opponent's team, then it could work (but how often does that happen?).
However, a Gigalith, Forretress, or stuff like that can use Custaps very effectively. Pretty much any pokemon with sturdy can guarantee 2 turns to do whatever you want with a Custap, which is pretty nice.
One more thing. Why would you use Brave over Adamant? Also, those 252 EVs are better used in HP thanks to his already gigantic Defense.
It doesn't really matter :P
Lith doesn't need Speed OR Special Attack.
And I'm using it as a lead so I'll be taking more hits with more defense from physical attacks, and when it comes to Things like Surf, Focus Blast, etc The posibility that I'll get a sturdy to activate is higher without HP.
Win, Win :P