Very, very, very normal, and it's NOT "not working"! Your toddler is just too young for you to see it working, or maybe you are focusing on the situations where it's not working and not noticing all the things he has learned to leave alone. Here's an excerpt from an article I wrote when my son was younger; he's almost 5 now, and there are still some things he just can't resist unless we put them out of sight and distract him--but don't you sometimes get that way, too? I know I sometimes have to hide the cheesecake in the back of the fridge and go out for a walk!
Babies are capable of controlling some impulses, some of the time—they just aren't as good at it as older people. Babies are capable of learning that something they do causes something else to happen—they just aren't familiar with as many action-reaction pairs as older people, and they don't have as much logical reasoning ability. These are skills that develop gradually, so we can work to encourage them rather than assuming they don't exist.
We never "babyproofed" our home. We wanted Nicholas to be able to cope with visiting places that aren't babyproofed (which happens a lot) and, well, we just have a lot of clutter! What we've done, as it comes up, is to move the things that either (a) he could damage quickly and we'd be really upset if he did or (b) he's consistently finding hard to resist. For example, our CDs were in both categories: the cases break easily when dropped onto a hardwood floor, broken cases are very annoying, and at about 10 months old he was taking every opportunity to go over to the CD shelf and take each one and glance at it for two seconds and then whang it to the floor. This fit both (a) and (b), so we moved the CDs to a higher shelf and moved the books that had been on that shelf to the lower shelf. We also have a few CDs on another shelf that's just above the arm of the couch. At 15 months, Nicholas learned to climb onto the couch and lean against the arm such that he could reach up to grab those CDs, but he was more controlled than a few months earlier: He held each one longer, then set it gently on the couch instead of throwing it. When we'd say, "Leave the CDs alone!" he'd put the one he was holding back into the shelf and smile and clap. We'd say, "That's right!" Impulse control! Following directions! But he was able to resist for only about two minutes before he'd be at it again. We'd redirect his attention to some toys, and we planned to move the CDs to eliminate the problem...but he lost interest in them after a month or so.
With things that we don't move out of reach, we demonstrate responsible handling and lower our standards of neatness. For example, books: We modeled how to hold books and turn pages, naturally, because we read a lot. When examining a specific book, Nicholas imitated our behavior very well. However, he also liked to take books from the shelves and put them all on the floor as with the CDs. We'd say, "One book at a time!" and try to interest him in one that was already out. We'd encourage him to help put them back on the shelf; that sometimes worked! Mostly, we accepted that this taking-them-all-out was something he really enjoyed and that he wasn't doing much damage. We gave up keeping the books on the lower shelves in any particular order and tried to re-shelve them such that they fit tightly and were harder to pull out. We also removed the dust jackets from books that have them because they're so easy to tear or crumple. From the very beginning, it was rare for Nicholas to tear a book (other than dust jacket) but when he did, we made it very clear that this was unacceptable: "NO! We do NOT tear books! Oh, my poor book, all torn! Sorry, I can't hold you now; I am busy fixing the book. See, I have to tape the page back together."
Another helpful strategy is to put some of his books and toys on the edges of shelves in front of our stuff so that when he starts to go for our stuff he gets interested in his instead. This also means that toys are handy from almost anyplace in the house we might be, enabling us to grab something when he needs to be redirected.
