everyone has different views, if i have a pair here for boarding and one if poorly, i take both, because i dont want to be responsible for the break up of a bond.
However, when its my own i dont. Jelly went with Peanut once and the vets called me to come and collect her, because she was stamping, biting the bars and was beating up peanut, she was so bored. As soon as she got home she flopped out and didnt care. When he came back a day later, she was so happy to see him, but...she didnt sppear to "miss him" when he was gone.
Now i have a trio it isnt practical, so i still only take the one bunny who is going. My vets are undertsnaing though, Jelly wouldnt eat after her dental and they wanted to keep her overnight, and she wouldnt be allowed home until she had eaten.
I told them once she saw her friends she would eat, so they let me take her home at 4pm, on the promise she would be back if she didnt eat. I literally opened the carrier, she ran to them, i chucked in some greens and she ate with them.
theres alot of exceptions to the rule, and i dont think theres any right or wrong solution.