I always have the right amount of well-formed (and well-spanned) TD and TR, making my markup actually logical and simple to understand. Which is not the result we get from open P.
I stopped closing <td> and <tr> because I found the (completely valid, completely unambiguous) practice of dropping the closing tags dramatically reduced the visual noise and clutter, making it easier for me to read my own tables.
If you say so, de gustibus. You might be making life marginally easier for you, to the detriment of any tool (or person) that has to parse your output.
