How does the New Rate System with Additional Services and Rate work?

I haven't booked with Rover in about 2 years so the new system of an additional hour and additional animals are new to me. Two years ago I booked for 8 cats for $20 per check in visit. So with the new system each additional cat is $8. Does this mean my new total per check in visit for my 8 cats is $84? If so, how is that logical for an hour visit? I would understand if that was an all day or few hours long visit, but it's an hour.