html table simple question about column width: should I type width="50" at every <td>?

[NumNoum]

You have 3x2 table:
<table>

<tr>
<td width="50">
</td>
<td width="40">
</td>
</tr>

<tr>
<td width="??">
</td>
<td width="??">
</td>
</tr>

<tr>
<td width="??">
</td>
<td width="??">
</td>
</tr>

</table>

The question is: Do you recommend to put "50" and "40" instead of "??"s ?
Thank you.