After the way the fight with Aizen and Gin went down, the chase after them by Ichigo and Isshin is pretty much expected. But with them spending some time in the Precipice World, which isn't acting quite normal at the moment because the Cleaner isn't there to make sure that nothing hangs out there, it's an opportune time to work without any real restrictions. Isshin does reveal an interesting little nugget about the place in that it was a location where criminals were once exiled to and they'd either end up absorbed into things or crushed out by the Cleaner itself. Ichigo's worked in this kind of training place before, having dealt with the special space that Urahara has, so he's ready enough to adjust to this and get to work.
And that work is to learn the Final Getsugatensho, the finishing move that should work on Aizen. It's not something you'd expect him to learn quickly which is why there's the advantage that Isshin figures it'll take three months time in that space for the Cleaner to be properly fixed and revived by members of the Soul Society. That'll give Ichigo plenty of time to find the answers that he needs in order to become stronger. Bleach runs through all of this fairly quickly, giving it a whole lot of tension and importance in the first few minutes, before shifting to the light material of the World of the Living itself. That place isn't exactly going all that well right now as noted by a few people there as much of it seems to have come to a standstill. Seeing the way Aizen and Gin just stroll with confidence through it is particularly chilling.