Points of view in creative writing

There is a general modern trend to believe that writers cannot change the point of view in one single story when it is written from one character's perspective. I have read this in online forums and critiques of other peoples' stories. There may be editors out there who express this idea but this should be considered a personal opinion, and an opinion is not a rule.
 I am reading The House of Mirth and found that the author of this book tells the story in second person from the main character's perspective (Lily Bart). However, whenever Lily has a conversation with another character the writer ventures to get inside the other characters' minds. We learn something about the feelings and emotions of the characters interacting with Lily by getting inside their minds even though the story is told from Lily's perspective; in other words, the writer becomes omniscient at times.
   Have you ever tried this? Do you feel uncomfortable when a writer does it?

New tenants over our door

We have new tenants: a family of robins built a nest over our door. I took a picture of their beautiful nest without disturbing them.

 Robins are very cute. The American robin's chest is orange. Its eggs are light blue. Robins hop along the ground after rainstorms, or in freshly overturned soil, looking for worms and insects. As harbingers of spring Robins presage new beginnings.