The default values for trimFactor, sparsity, and precision should be set to values that would be most suitable or performant for QE range values that span the entire domain of the field type.

edit: striking off precision, since it currently does not make sense for it to have implicit defaults. It can only either be undefined or explicitly defined.

update; per the attached document from the crypto team, the default trimming factor should be 6, and the default sparsity factor should be 2.