For many years pre-Covid, there were park-to-park buses.
When there was no park hopping after the Covid shutdown, there were no park-to-park buses.
When park hopping resumed. but with an after-2:00 limit, the park-to-park buses started at 1:00.
When park hopping resumed being all-day, the park-to-park buses began running "all day" again (although I understand they really aren't running often at all in the early morning).