There was quite a bit of discussion on this in the season one thread. In the second episode of season one, Glenn said that it was the first time he had taken a group with him into Atlanta; his other excursions had been solo. Presumably he focused on food and similar items, and of course that first time with a group got interrupted by the need to rescue Rick. After that, they only went back into the city twice - to retrieve Rick's guns and Merle, and to get to the CDC. After the CDC, they headed straight out of the city because the implosion would've brought walkers swarming. I wouldn't say the comics are irrelevant. The producers have been very clear that the comics are going to be the roadmap by which the series proceeds, but, yes, of course they are going to detour to differing degrees at various points. Shane may still be alive, but I expect they'll still hit most of the same "big" points; we are, after all, headed straight in the next episode for a location that was important in the comics. Plus Robert Kirkman is an EP and writer, so it stands to reason that there will continue to be significant overlap between the comics and this series. In any event, I don't think what sojourner posted is what Jenner told Rick; I think it's the other issue that has also previously been mentioned in spoiler code. That one results in some significant storytelling, so I'd be surprised if the series doesn't go down that road.