I think it depends on what you can do ideally and maintain consistency throughout the book/series. You're setting an expectation for your readers. If you set it high release rate at first and have to dial it back a few times, you're introducing variability in your schedule and messing with those expectations. Sure, its okay to have to change (in fact I'm slowing down due to an evolving family medical issue that's straining us), but you don't want to keep being unpredictable.
Also, readers are human and understand little blips, but again I think considerations for consistency is more important than fast releases out the gate that are unsustainable.