I just got a new toaster. It came with an insert recommending against using only one slot when toasting, as doing so causes uneven browning. A handy chart showed what each side of a piece of toast would look like on each setting, and in each case, one side of the toast was considerably darker.
Why would using only one slot in the toaster produce such uneven results? Or to put it another way, why would using both slots toast each slice of bread more evenly?
Sounds like they’re in the pocket of Big Bread.
Oops, no jokes before serious answers. Sorry.
Is there a barrier between the slots with a heating element for each slice or is it open between the two with a common heating element? In the second case I could see the heat from the bread radiating into the unfilled slot and escaping, not charring the bread completely.
Most of the toasters I had over the years recommended one of the slots over the other for singletons. Never seen an insert.
The real question is… who are they pandering to? Like who only eats a single piece of toast at a time?
Must be a function of a 2nd slice absorbing heat, whereas if there’s no 2nd slice, more heat goes to the adjacent side of slice 1.
I’ve had toasters way in the past that said use this side for one slice, but not lately, and I don’t remember ever seeing the effect described in the OP in any toaster.
sounds like a perfect question for an experiment. What make and brand? I will try the experiment with my toaster as well. Everyone in the Dope needs to contribute data to this important question! Please report back on your results. 
The real question is, why do people buy “toasters” when “toaster ovens” cost about the same and do so much more.
We have both. But if we just want to toast a bread or a bagel, the toaster is quite a bit faster.
One thing I hate about most toaster ovens is that you have to turn a timer dial in order to toast. Rather than press a single button or lever, you have to turn the timer dial according to how long you want to toast, and typically the toast range of the dial is pretty small. So it can be a hassle to try to turn the dial to the exact position for a certain level of browning. Dedicated toasters are simpler. There’s a slider for doneness that you can leave in position and then just press the lever to start it. For people who do toast 99% of the time, a dedicated toaster will likely be more convenient.
It’s been decades since I toasted more than one slice of bread, one bagel half, etc.
If one eats low-carb, one slice of bread is already too much.
I have a toaster oven and don’t have a toaster. But a dedicated toaster is simpler, faster, and makes more even toast than a toaster oven.
While we’re on the subject, why do so many frozen dinners have a Do not heat in a toaster oven warning? I’ve lived dangerously and done it anyway a number of times and have had no explosions or fires result.
Seriously, I’m guessing the top element is too close and might burn the top of the item a little, but I do love those Maillard reaction products.
OK, I guess toasters are quicker than toaster ovens for toasting bread/bagels/etc. I did not realize this, I guess because I never am in a hurry when cooking.
Take that toaster back and get one that works correctly. In this day and age, there is no reason to put up with such poorly engineered nonsense. I use a 60+ year old Sunbeam and it has no issues with single slices, and it lowers automatically!
If I’m cooking, I’m hungry.
Same here, but I find that prolonging the wait to satisfy a hunger makes it even more satisfying.
Says the guy who often puts dinner on the table at 9 pm. 
Technology Connections, is that you?
Nah. I’ve had that toaster since well before that guy had his YouTube channel up.
My god, we’re getting ready for bed at 9 pm.