We just returned from WDW this past weekend and I had booked both CRT and Akershus for meals. Our reservation at CRT was 4.05 pm so we were one of the first to be seated for dinner. As such, we didn't have to wait for a previous group to leave and were seated immediately. Service was awesome and super friendly, and I thought the princess interactions were lovely - each princess spent just the right amount of time at each table, taking pictures and making small talk. We didn't leave until @ 6.45 pm and the lobby was packed with people who were waiting to be seated. Cinderella (who greets guests in the lobby) was just standing around, waiting for the next group to be let in because she had already had her picture taken with everyone who could fit inside the waiting area. I'm sure those with 6.30 pm or later reservations were going to be backed up by at least 30 minutes, if not more. Or the princesses / service would start to be super rushed and that would have sucked.
Now, it was a completely different story at Akershus. We had a 1.30 pm reservation for lunch and we didn't have to wait too long, so it wasn't like they were backed up. We were seated right after we got our pictures taken with Belle, who was the greeter (and who was lovely, BTW). Anyway, when the princesses came out to do their meet-and-greet, they practically sprinted into the dining hall and spent no more than 30 seconds at each table. Literally. Each princess, when she got to our table, it was like this: "Hello there, everyone" ... Grab autograph book and sign ... Take my five-year-old's hand and stand / pose with her, and she would scramble to get in place ... I'd take the picture, they wave good-bye, and with a swish and swirl of their skirts, they were gone. It was madness. Luckily, we had done CRT for dinner the previous night so we just got a good laugh out of it; otherwise, I would not have been happy at all. We had done Akershus on previous trips and always been happy with the interactions, so I was really surprised at how rushed everything was this time around.
Either way, no matter where you dine, maybe consider one of the first seatings for that meal so you don't have to wait when guests take longer than expected? One night, we had a 7.45 pm reservation at 50s Prime Time Cafe at DHS and weren't seated until 8.30 pm because of the back-up. It was not fun, to say the least.
Have fun!