Slices are a great idea until boss/alliance events don't use them.

Wumpushunter

How many slices have finished prodigal son and can throw all their health packs at Thanos and how many slices have hours left on the 7 day pve event jockeying for placement?  Not the largest issue facing d3 but one of basic fairness.

Quebbster

Slice 1 ended 5 hours before Come and get me started, slice 2 ended when Come and get me started.
Considering you have an 8 hour window to beat Thanos and you don't need a lot of health packs in the early rounds I don't see this as much of a problem.

halirin

Yep. Maaaybe a problem in theory. Definitely not a problem in practice. 

Pants1000

It is a little annoying.  I play slice 4 and was going for top 10, so the 2nd boss wave started before my final grind.  The early boss rounds are fast and easy so it wasn't that big of a deal.

i can't think of a better way to do it, so I wouldn't suggest any changes.

Wumpushunter

I play the last slice, there was 18 hours left on Prodigal Son when Thanos went live, plus having it at the same time for everyone those early people grab quick easy points on Rounds 1, 2 and even 3.

Quebbster

Slice 5 ends two hours before the third set of boss submissions start, right? It definitely seems possible to be done with the second set with plenty of time to let the health packs recharge, then you could do your end grind and then do the Thanos nodes later in the 8 hour window.
The devs did screw up bad in the third run of Galactus where the newly released Nova was essential and anyone playing his release event in slice 3+ couldn't do his essential missions (3 did get their rewards before the first mission change but 4 and 5 players flat out missed an essential mission), but that's probably the biggest problem that could arise and it has been avoided ever since.