Back to the original question…no, there’s no harm in shifting from D to N and back to D while driving. The automatic transmission will handle this just fine.
In fact just today I took a car on the highway, got up to 70mph, shifted to N and turned the key off. After coasting for 10-15 seconds I started the engine, shifted to D and drove on.
Thanks for your last two posts. But, sorry, I totally disagree that “no one really meant any disrespect.” You’ve got to be kidding, or you need to re-read the posts left here, as many show a sizeable amount of disrespect.
“…willing to be they’d all go out for a beer with you.” Never would happen.
Thanks for your post. Those who were sincere and didn’t make an issue over cylinder configuration, like you, were respectful and helpful. Thanks for being in that group.
Count me out on the beer thing.
You’re one I would count on on the beer thing, or any display of respect, when you have been totally disrespectful, sneaky to keep pinning me down on “what engine do you have” so you could really appear Big Man #1, or so you think.
Yeah count me out on the beer thing too but I sure could use a good rum and Coke right now. Been over a year. But if you are looking for peace love and harmony, there would be better places. But if you wanna know what an engine code is, this is the place. No one really cares if you have mud on your shoes or your tie is crooked but don’t say break instead of brake.
Which is funny because we had just the opposite impression when I was getting started in cars. Big loping V8s redlining in the 5’s while us college kids with 4-banger Hondas were somewhere between 6500 and the 8’s. But then you look at the F1 V8/10/12s of the era, screaming along at 15,000+ rpm and all your impressions fall apart. 
We can thank the Japanese partly for that change.
In their econoboxes they put overhead cams, then 3 and 4 valves per cylinder.
No point building the bottom end to run over 5000 rpm if the valves float or the engine can’t breath at those speeds.