Yes heuristic logic can have a role here, e.g. if list has length M and number of passes through it M, do N*M and if the result is over some threshold then make

Yes heuristic logic can have a role here, e.g. if list has length M and number of passes through it M, do N*M and if the result is over some threshold then make the effort of sorting the list. But a good value for that threshold depends on many factors, hence a heuristic may make sense in some scenarios. It's the same sort of pattern used with SQL query optimizers, e.g. cardinality of a result set is one of the key factors that influence how some query on that result set will be executed, e.g. whether to scan versus use an index.