It would be very helpful and instructional if people who plan on brooding chicks were to observe a mother hen caring for newly hatched chicks.
Up until a month ago, for the past nine years I've been brooding chicks in makeshift brooders or outside in my run. This time I permitted my broody hen to care for the single chick she hatched. What I noticed is that the chick was all over the place after day two. She didn't remain under the broody hen for any longer than to get a quick warm-up, and it certainly wasn't a warm environment like you would encounter in a brooder.
The last two springs, I brooded several sets of chicks outdoors in my run with the heating pad system. Again, what was very noticeable was the chicks, even when the temps were below 70F and sometimes in the 30s, didn't spend much time under the heat. They seemed to suffer no ill effects being exposed to very cool temps.
In fact, from my observations, they benefited by feathering out much sooner than indoor brooded chicks. All the chicks brooded outdoors, whether under a heating pad or broody hen, were well feathered by age three weeks. This single chick I have now is four weeks old precisely, and she has all her feathers except for a little bit of down sticking out on the back of her head. The other night I peeked at the chick the see if she was sleeping under the broody hen still. She was not under the hen when night came, but simply snuggled next to her mama.
People tend to judge the heat needs of baby chicks by their own comfort level instead of what the chicks actually require. They do not need a constant and uniformly warm environment. They are not cakes baking in an oven. One single heat source is all they need for the first month. The rest of their environment can be any temperature, even down to freezing and below, and they will be just fine.
So, yes, rigging up more than one heat lamp is not only unnecessary, but it's counterproductive and even dangerous. When those notorious heat guidelines were established, it would have been much more helpful if it were to be stressed that chicks need the benefit of cool temps as well as a single heat source, and that it's just as important to reduce the level of that heat on a regular basis so that the chicks can be weaning off heat right from the start. And that continuing supplying heat to chicks already well feathered is not a good thing.