Sensitivity of Schottky Diodes to ESD, effectiveness vs TVS diodes
The part you link to shows the inherent problem with all TVS devices; the clamping voltage has a huge range:

Looking at the 7.5V part, it has a reverse standoff voltage of 7.5V (quite reasonably). At this voltage there will be no more than 50μA of leakage current, but the maximum clamping voltage (at maximum clamp current) is 12.9V.
The Littelfuse devices are very fast acting (because the internal parasitics are minimised) but I have used some parts that do not properly clamp for several hundred nanoseconds even though the manufacturers model showed instantaneous clamping (and lightning testing destroyed several parts before that was tamed with added circuitry).
To guarantee clamping voltages, I would normally use a pair of schottky diodes with a series resistor (to limit the clamping current) and a small capacitor (not always possible - high speed data lines are the very devil to properly protect).



simulate this circuit &ndash; Schematic created using CircuitLab
With schottkys, be careful of reverse leakage; a properly chosen part will be ok, but the leakage is exponential with temperature and can cause thermal runaway in certain  circumstances.