Time is linear, and it is not.

Basic concepts:

Events happen in a linear manner because of the law of cause and effect. The smallest event we can observe is defined by the so called Planck scale. An event that is shorter than the Planck scale can't be observed anymore, at least not from within this universe. Your ISBE consciousness, while inside a body, is centered – it rests half-way between the Planck scale and the border of the observable universe (which is just a limit of observation, not a real border).

Purpose of the universe: It basically is a big memory generator. Everything that happens inside a universe is happening – and is being stored – in a linear manner.

But: The ISBE itself is not bound to observe cause and effect in a linear manner. Courtney already explained this: The ISBE can travel time and space at will. That's why it doesn't need memory.

Time slips, time pockets, and similar concepts are perceived when the ISBE is not bound to the physical matter of the universe.

You can compare time with swimming in a river. As long as you're swimming in the river, you are bound to the flow of the water. But you can leave the river, sit at the riverbank and observe, or even walk back upstream.