Cliently can help you split a long list of imported contacts across multiple team members in a round-robin method.
Import your contacts
View the list of imported contacts in the Real-time View
Click the "More" button
Select "Change Ownership"
Click in the "Select Owners" box
Choose the team members that you would like to split the contacts across
If you have 100 contacts in your list and 4 team members are selected, each team member will have 25 contacts assigned from the list.