I really want to know why they have already decided its a 2 day assignment. That seems fairly ridiculous to me in light of Hamilton's early return from the DL, and the slump Kinsler was in prior to his DL trip. In my opinion, the Frisco appearances should last as long as they need to last. If Kinsler is hitting the ball and seems like he is unaffected by the Hamstring, I see no reason not to bring him up in 2 games.
However, if he is still having issues, I see nothing wrong with using the whole 30 days if necessary. I'd just hate to see a repeat of the Hamilton fiasco.