I'd also like to point out that they're all normal people. Only Rick and Shane have any sort of comprehensive firearm training; only Daryl is an experienced hunter and woodsman. None of them have crazy survivalist experience, none of them have had to deal with making armed, secure camps before, and none of them are exactly Mensa level. The fact that they're making mistakes only a few months into the zombie apocalypse is perfectly reasonable, and that they haven't changed their habits enough to be optimized for extreme safety is to be expected.

Spoiler
Show
Expecting Lori to immediately come out and say she's pregnant, for example, is silly. She and Rick still have problems, she doesn't know exactly who the father is and Shane could go even more nuts if he thinks he's having his own kid now, and just an episode or two ago she expressed sincere doubts as to whether this world is one in which she wants her child(ren) to live. Yes, logically it would be best to simply come out with it as people will find out eventually anyway (unless she gets it aborted somehow), but how many people do you know that behave logically all the time? How many people in survival situations are always thinking clearly?

The watches being ineffective is debatable; obviously we're not going to see every single night, especially if nothing interesting happens that night or whoever's on watch deals with a walker with no incident. We see the watch fail a few times, sure, but one person or even two cannot see everything.

On Shane and Otis being the ones to go: Glen was definitely elsewhere. There was no time to waste as Carl was near death. Otis had firsthand knowledge of both the school and the equipment they needed, and really, acquitted himself pretty well; just because he's fat doesn't mean he's not useful and should be immediately dismissed. I admit that the situation where Shane shot him was a bit unclear (to me at least), but actually I liked that about it. Shane clearly thinks he did what he had to do to survive, and Otis wasn't very hopeful about their chances either, but there's always some ambiguity in a choice like this. Shane could be right, and he took the option that led to one of them getting out of there and thus saving Carl; TBH I can't blame him for choosing himself to live, if that was the case. Or, Shane could be wrong, and his increasingly narrow focus is causing him to make bad decisions, not just morally questionable ones. I like that there's arguments for both sides.

Also, if Andrea doesn't lose gun privileges for this, they deserve to get shot. I was shocked that almost no one seemed truly angry with her; that was a massively boneheaded move, especially after all of her grandstanding about how she deserves a gun. She's almost becoming a straight liability at this point, which I'm surprised by; at this point in the comics, she's one of the more levelheaded hardass characters in the group, and the best shot by far. Her characterization is going farther afield than I expected.