This is, of course, a trick question. The answer itself isn't the important part - the important part is that your readers will notice sameness when they encounter it, and expect it to mean something. Which in turn means that if you don't want the sameness to mean something, you have to work towards making every scene different.
Let's get a bit more concrete about when sameness means something.
Let's say you're starting your story with your main character walking
into a confrontation with a parent, and the main point of the story is a
change in the relationship of that character with the parent. Then it
makes sense to put in a scene at the end where there's another
confrontation between the character and the parent, and it comes out
differently. The repetition is noticeable, and it means something: it
means the character has changed, allowing a different outcome from a
very similar situation.
In The Princess Bride, we see repetition between the scene when
Buttercup first gets introduced to her people as a princess, coming out
on the red carpet, and the scene where she walks out with the queen's
crown on ("at noon she met her subjects again, this time as their
queen...") and gets booed. In the first instance, she's detached but
accepting of the situation. In the second, she has her detachment and
her acceptance called into question. It creates a terrific contrast, and
that second scene had me going "No, no, no!" the first time I saw it.
(And it has the boy doing the same thing.)
In The Lord of the Rings there is a repetition of the scene inside Mount
Doom - between Elrond and Isildur in the first instance, and between
Sam and Frodo in the second instance. Part of the power of the
repetition comes in our desire for all the adventures to have changed
things and made the situation different, so that Frodo won't fall into
the same trap - and yet he does.
In a situation where two scenes are noticeably the same, readers will
conclude that any differences they can find will be seriously
significant to the story.
Now let's talk about when it's important to make every scene different.
Take my recently completed novel as an example. I have a society going where
the nobles get messages via servants, and in which the sending of
messages is quite common and sometimes quite important. Naturally, this
means I have a lot of scenes where servants are delivering messages. The
danger here is that there would be too much similarity between the
scenes of message delivery - causing people to invest significance in
differences between the scenes that really have no particular import.
Then of course as we go on and there are more instances of message
delivery, it could get extremely repetitive.
In this kind of situation I pay very close attention to which aspects of
the scene are important. Is the location where the message is received
important? Is the method of delivery (paper or recitation) important? Is
the content of the message important? Is the character's reaction to
receiving the message important? When I write the scene, the important
elements need to stay, but those of less importance can just be skipped.
So when Tagaret gets a message too sensitive to be written down, he gets
it in his own room via recitation - and I make sure to show that. When
another message comes and the deliverer wants to be anonymous, Tagaret
gets a piece of paper slipped under his door. When the message is too
urgent to let the family enter the house and relax before receiving it, I
have the First Houseman meet them in the entry vestibule to deliver the
message. But when Tagaret gets the message that a close friend has
survived the threat of death, it's not the method of delivery that's
important, but Tagaret's reaction - so I skip the message delivery
entirely and go straight to Tagaret's post-message emotions and actions.
Watch out for small details that can become repetitive when you're not
paying attention, such as the way you have people respond to danger, or
the way they approach doors. If you're always describing these the same
way, you're giving your character a habit - which may be charming and
work great, or which could be entirely distracting from the conflicts of
The other place where sameness can cause trouble is in larger, more
important events. Maybe you're writing a book where a politician is
trying to get something done and has to give a number of important
speeches. It could turn out to be really awful if everything surrounding
those speeches is the same, especially if your politician is giving the
speeches about the same topic, just to different people. In that case,
it's worth working hard to create different contexts for the similar
In my novel, there is a point when the story events start
being organized around a political process called Heir Selection. In my
Varin world, twelve candidates compete in several rounds of voting so
that one can be selected as heir to the throne. The votes are all cast
by the members of the Eminence's cabinet. We start with the Round of
Twelve, then three days later is the Round of Eight, three days after
that the Round of Four, and three days after that the final round. I
think you can see the trap. If these events are not to become very
repetitive and boring, they must be very different from one another.
They must take place in different locations, the type of test put to the
candidates must be different, etc. - but even that is not quite enough.
I've also found that I have to make sure that I use different points of
view, and even take focus off the content of the event. The Round of
Twelve is handled in the point of view of one of the candidates on the
stage in the Hall of the Eminence; the Round of Eight is outside in the
Plaza of Varin, and the questioning that the candidates have been
subjected to is not even part of the event. While the Eminence
announces the results of the question session and introduces the four
candidates who will be moving on, I stay in the point of view of an
audience member who doesn't care at all about what the Eminence says
because he's busy trying to stop one of the candidates from being
assassinated. My sense is that for the Round of Four I'll be back in my
candidate's viewpoint, because this is a spot where his actions during
the competition are absolutely critical - but for the final round I
suspect the question of the results will be far more important than any
character's actions during the ceremonial portion, so the ceremonial
part will most likely be omitted.
As I go through this I'm noticing a pattern, which is to say that any
time you have repetition it's important to keep the primary focus
different. Try to identify what's most important about what is
happening, and stick to that. Look around for ways to change setting,
character, etc. so you are not simply falling into a reader's
comfortable expectations. When their comfortable expectations are being
met, readers are far more likely to skim or skip. It's the focus on
difference that will keep their attention riveted to the page.
It's something to think about.