One entry is defined as (1) the same importer of record, (2) arriving on the same vessel, and (3) entered at the same port of entry. Therefore, an entry can have any number of shippers, invoices, house bills of lading, or containers. In fact, one entry can have multiple master bills of lading, as long as they're consigned to the same importer of record.
Something to consider when constructing large entries is the probability of an exam and the financial consequences of a long hold. When an entry is selected for an exam, all containers and bills of lading are usually held. Therefore, some best practices include limiting the number of containers per entry to no more than 3 or 4 or entering FDA regulated goods separately.