[db_admin]

No you are not allowed to do that. A grey square excludes the letter from the position, regardless of any yellow squares.

[pricci]

You are correct. Words with repeated letters are not a good strategy in this game.

[JoshTriplett]

Words with repeated letters are a great strategy, as long as you know or strongly suspect the letter isn't in the target word, and the letter is rare so eliminating it doesn't eliminate much.

[skeaker]

They are a fantastic strategy, though if one happens to rob you of a lot of remaining words, you should undo it.

[pricci]

Hmm, that was the case when I tried and I jumped to the conclusion

[nebulous1]

I'm not sure about your conclusion here. If we don't repeat the letter then we're going to have information about another letter, which we don't want.