If anything spills, then it can get inside the drawers and doors.

It depends on the door and drawer style. Are they full overlay? I would say they should at least overhang the fronts of the doors and drawers.

I just saw a pic where someone did this and I thought it looked really strange. And, as cpartist said, the overhang is so that your cabinets don't get all the drips.

@kelleg69, can you post the pic or a link? I’m having a debate about this and would love to show an example.

It's a very nice modern look to have flush countertops with the cabinet fronts. We've done two modern kitchens, and the first one we had a 1/2" overhang. The next one, my DH really wanted flush so we did it. We loathed the practicality of it on a daily basis -- mainly because when you went to wipe crumbs off the counter, you can't sweep them into your hand. You put your hand right up to the counter edge/cabinet front, and sweep in crumbs, but half of them fall on the floor. They didn't go in the cabinets. Just on the floor. Cursed it daily. Even though i really like the look a lot.

Next kitchen will be back to a 1/2" overhang. At 40-41", you have plenty of room to not worry about half an inch.

OP: When measuring aisle width(s), don't forget to take into account your drawer/hardware projection -- i.e., how far they'll stick out from the cabinet.

Have you picked your hardware? I would make sure the countertops at least overhang the protrusion of the hardware. Otherwise spills will land on the hardware, and if people tend to lean on countertops while in the kitchen, they might be leaning on the hardware (a bad thing for cabinets).

I can't tell you what the overhang was in our kitchen before we redid it, but there was an overhang -- about the depth of the door panels from what I recall. But the had applied moldings on top of that and a recessed panel in the center. Anything that dripped would go over the moldings and into the recessed panel and then the moldings at the bottom -- and all the crevices along the way. They were a nightmare to clean. What I would have given for a little preventative measure.

On the other side of you equation, I had 36 inch aisles. We had to keep the same footprint, but were able to streamline things a bit (move pantry, slide the ovens down, trim the island slightly) to pick a a little room, but I have no more and probably less than you do. If anything, I would add another 1/4-1/2" to either side of my island top because I still have cabinet drips where DH preps. Not as bad, but not worth a half inch to an inch. Make sure your work zones and traffic ways don't make the paths overly crowded when multiple people are in them. If you are lucky enough to have a one person work space, you will be fine -- might even prefer a few inches less. There is an efficiency factor to it -- a tradeoff to lots of aisle space. There was a person who used to spend a lot of time here before Houzz who referred to her cockpit kitchen -- everything close at hand.

The post above mentions hardware -- there really isn't any benefit in terms of aisle space to having flush counters if your hardware sticks out another 3/4" to an inch. It's like giving up coffee for energy drinks.

I found this pic of a flush countertop. I like the look, but can see it would be highly problematic.

In my kitchen in the cabin I have to have the overhang on the peninsula side of the kitchen be around 1”. But it’s bar seating with just a bookshelf cabinet on the sides so no prep or such going on there.

I have about a half inch past my drawer fronts. More would be better. it's just messier.

I have flush countertops on my island. Wasn't by choice, it was either that or buy a 3rd slab. I don't like it. I haven't spilled anything(in 3 years) so I can't speak to dripping problems. But as mentioned above, you can't put your hand under the counter to catch crumbs so they fall to the floor. I also don't like the look compared to the perimeter cabinets(which have standard overhang.

Here is a picture: