- Make a full round of attacks
- Make a full round of missile attacks
- Move a number of feet equal to your movement rate in inches. (basically 2" or 10' if your movement is 9" or 12", or 1" or 5' if your movement rate is 3" or 6"
- Cast a one segment spell or begin casting a longer spell
- Perform any action that can be completed in one segment.
That many attacks are rolled, because the damage they do to you in the surprise round is much more devastating then any wound they could give you during a round of combat in which you are prepared.
Now of course, this all falls apart when the surprise segments suddenly turn into real segments of activity. In that case, you wouldn't still be surprised after someone struck you for the ninth time in 54 seconds. I imagine it would be difficult to remain surprised for that long.
So as long as these represent real values of explicit time in which you are tracking activity during the round then my player is right. If it instead represents the damage done to you while surprised, or what you can reasonably accomplish before your opponent is prepared, then it works quite well for that purpose.
We have agreed to compromise on using a d6 for surprise.