Correcting errors and karma

An easy way to win cheep karma on LW:

  1. Publicly make a mistake.

  2. Wait for people to call you on it.

  3. Publicly retract your errors and promise to improve.

Post 1) gets you negative karma, post 3) gets you positive karma. Anecdotally the net result is generally very positive.
This doesn’t seem quite sane. Yes, it is good for us to reward people for changing their minds based on evidence. But it’s still better not to have made the error the first time round. At the very least you should get less net karma for changing your mind towards the correct answer than you would for stating the correct thing the first time.
Questions:
Is there an advantage to this signalling-approval-for-updates that outweighs the value of karma as indicator-of-general-correctness-of-posts?
If so then can some other signal of general correctness be devised?
If not then what karma etiquette should we impose to ensure this effect doesn’t happen?