: Not sure what the Requiem to Gamma Halo distance is, nor am I sure about
: Gamma Halo to Earth, but if Gamma Halo is also not far from Earth, then
: the Halos aren't really spread around the galaxy but are preferentially
: clumped around Earth (Alpha and Delta seemed strangely close by too).

: It took over about a month and a half through a Forerunner portal to go from
: Earth to the Ark one way. Requiem to Gamma Halo to Earth can not be a
: trivial amount. Given the game's timeframe, Spartan Ops occurs 6 months
: after the Didact's attack on New Phoenix, so how long does the complete
: Halo 4 campaign take? I wish we had some answers.

Not sure about Requiem to Gamma Halo, but Gamma Halo to Earth at least is implied to be pretty much a few minutes for the Chief. There's no cutscene between the Didact entering slipspace in Composer and the Broadsword section on Midnight, and that section begins with Cortana confirming that yep, being under the Didact's shields is working.