It's exceedingly rare you will face 5 unshielded targets, making one of the main benefits of TS3 moot.
Seconded. TS is best used against tightly clustered, unshielded, targets so that the Kinetic Splash Damage stacks up to ridiculous levels.
Unless you're planning to strip the shields yourself, or you have a trigger-happy buddy with Cannon Scatter Volley and/or Gravity Well, you're probably better off using Attack Pattern Beta 2 instead. My own preference for the Excelsior would probably be something like TT1, BFAW2 and APB2 (with at least 1 Purple 'Tac Team recharge' Conn officer DOFF).