The two most important factors that determine the number of records created are:

Whether the titles are the same or different

The designation system of the serial, i.e., whether all titles share the same numbering scheme or each has its own

Other facts that might influence the decision are:

Whether the works are intended to be used together or whether they stand alone as separate items.

Whether the items may be purchased separately

The frequency of occurrence of the related item

Whether or not both items have the same publisher

Presence of sequential pagination

The impact on serial check-in

See also:

17.1. Introduction