Just finished Episode 5 last night, and it's just now starting to hit me how much I'm going to miss the adventures of Max and Chloe. Arcadia Bay was an interesting place, and I'm pretty excited to see where Dontnod takes us next.
After spending some time catching up on this thread and sifting through all of the discussion about how Max's time powers work, I'd like to add something of my own: I think there's a major difference to be considered between the "rewind" power and the "photo diving" power.
I suspect that the Rewind power does exactly that. It rewinds events exactly to how they were a few moments ago. This allows for things like Max's "teleportation" into Wells' office to work, since she can will the world around her back into place with no effect to herself, and since things are just being rewound like a tape multiple timelines are not being created.
Example: If Max botches her attempts to warn David in the Dark Room multiple times, it isn't leaving behind a growing bodycount across multiple timelines. It's just one string of events, being altered over and over until a conclusion is reached that is suitable for Max.
Photo Diving works a bit differently. More than just a huge rewind, Max forces her consciousness backwards into a previous Max and then proceeds to poke around until she finds a way to accomplish her goal. Once her mission is completed, the Max Consciousness is forced onto a newly branched alternate timeline, where she will now take the place of the Max that was previously there.
Example: Max hides William's keys. This forces the Max Consciousness onto Timeline B, where William lives and Chloe is paralyzed, while Timeline A continues to exist, the events of that timeline march on unabated. As to whether or not Timeline B is erased when Max returns to Timeline A is left up to interpretation. Perhaps her attempts to return to Timeline A actually result in Timeline C.
As an additional thought... I find myself wondering if Rewind has more of a physical toll on Max (resulting in things like general exhaustion, the sudden inability to use her power) while Photo Diving is more damaging to the general space-time continuum.
Edit: Here's a quick and dirty graphic to illustrate what I mean.
