Roast chicken and burnt beets

A couple nights ago I set out to make roast chicken and vegetables. This is what I make for supper when I want something comforting but dead-easy. I usually follow Chatelaine's recipe to a perfect roast chicken; the bird is stuffed with lemon and garlic, then rubbed with butter and dried herbs. (You can watch me make it here: http://en.chatelaine.com/english/video/food/article.jsp?content=20080304_210543_6776.) Now for where things went wrong. I usually slip a baking sheet loaded with oiled vegetables on the oven rack underneath the chicken so they can roast all together and dinner is done at the same time. This time, however I was roasting a mix of little golden beets and larger red ones. Needless to say, the golden beets were done before the red ones, so I decide to leave the red in the oven while I ate the rest for my dinner. About an hour later I had that moment, you know the one where you remember there’s something in the oven and make a run for it. Despite being a trained chef, I’ve had that moment far too many times. This is what I found when I opened the stove. Poor beets, they were like petrified wood. I had to throw them out along with the baking sheet. I think it’s fine to roast different-sized vegetables in the oven and remove as they’re done. But I messed up by not using a timer. Of course those slow-poke beets would slip my mind, while I was enjoying the roasted chicken and vegetables. Even though I religiously use a timer at work, I never do at home. Needless to say I’m back to using the timer at home too. At least a little while maybe until the smell of burnt beets leaves my apartment...