Personally, I don't recommend doing a "full breakdown" of the lock unless something is broken in it. There is too much chance of breaking the mainspring and losing the fly if the lock has one.
Now, removing the lock and wiping off what little fouling that might exist on the inner workings and the outside, that's something I recommend doing every time you clean the gun. It isn't absolutely necessary but it gives you the opportunity of oiling all of the moving parts to keep the lock in good working order.
