Under what circumstances, when a searching operation is needed, would Sequential Search (Algorithm 1.1.) not be appropriate? (pseudocode)

sequential search(algorithm 1.1) the book

Algorithm 1.1 Segrontial Search Prob.cm: Is the key x in the array of n keys? Inputs (parameters): positive integer n, array of keys S indexed from 1 to n, and a key x. Outputs: location, the location of x in S (O if x is not in S). void seqsearch (int n, const keytype S[], keytype 2, index& location) { location = 1; while (location n) location=0; }