Crowbar circuit design: choosing the correct parts
If you replace the standard fuse with a PPTC, it will work in &lt;1s safely and be resettable with a power cycle.  These will operate at a component temperature of 125'C which is safe for ceramic and draw low power.  There is no time to trip variation as the trigger is defined by the voltage threshold.
For a more precise threshold, D1 could be replaced by a TL431.
The inductance in the loop must be kept low relative to the ESR as it resembles a high Q series RLC circuit with a natural overshoot. This is not difficult for normally small layouts but may be considered for dry contact step inputs.
final comments
For a detailed analysis, one needs to know the energy stored in Capacitors in the source and load as the PPTC is charging them up and the driving impedance of supply that may have failed with overvoltage and its max loop current on crowbar.  Also if there is an inductive load, the flyback voltage must be considered too.
This is a tradeoff with the load regulation ripple you can tolerate as defined by the total series ESR / pulsed load dynamic resistance and the stress on the wire junctions of all components including protection devices.   This is beyond the scope of this question.
There is also the question of reliability for the supply, the fuse and the sustainability of operation and the level of transferred overvoltage from outside forces. (e.g. lightning).
This often requires a more comprehensive approach with snubbers , over-voltage absorbers and serial current limiters and depends on the quality of the design specs required.