Some puzzles require guessing

[gavin71]

I have found that almost all of the puzzles with low completion rates (less than 30%) require guessing. That is, the clues are insufficient to solve the puzzle. This month, I'm going for 100% completion, so I keep guessing until I get them done, but it's annoying. Here's one example.

<http://www.logic-puzzles.org/game.php?u=6af2ed56049b00c550123484d0ed190b>

I looked for a similar thread and didn't see one.