This thread fails to address the crux of the argument, mainly that the content of the internal monologue is the key factor.
I agree with this, but you clearly don't understand what it mean.
Character thoughts should only be used when there's really no other way to provide the information. It's that, and not the effective interest of the information, that is the real key factor.
For example, showing a picture of a beautiful woman and then the character thinks "man, she is pretty" is treating the audience like an idiot.
While I agree that the information by itself can be relatively useless, showing the character thoughts is the only way to provide it. Yet, when I say that the information is relatively useless, the important word is "relatively".
Depending on the photo itself, it can give some important hint regarding the MC. If it's a 40yo woman, he's more attracted by mature women. If it's a motherly figure, there's chance that he's submissive, or at least docile. If it's an alt girl, he probably like them "weird", or at least with a free spirit. If it's a sportive, there's chance that he like them independent. And so on.
However, showing that same beautiful woman and then the character thinks "We used to be close, but once puberty set in the normal separation girls and boys experience seem to be magnified and we might as well be complete strangers these days." This actually tells the audience something about the character that you couldn't get across in normal dialogue in a natural way.
How is it more useful to know about a character that we will probably never see, nor hear about, precisely because they "might as well be complete strangers" ? At most it give us information regarding what the character liked in the past. But since it was before his puberty, it's now totally irrelevant.
But the main problem is that there's absolutely no need to rely on the character thoughts to provide this information. At most it's laziness, at worse a lack of imagination. There's so many way to express the express this without having to rely on thoughts. In fact, unlike for the "she's pretty" example, this can even be done without writing a single word.
You can do it passively, relying on a series of photography. Whatever if they are in a family album, or in display in his bedroom, they were take through the character youth, and until he hit puberty, the girl is always on the photo. This while the photos themselves express how close they felt at this time. If was happy times, reason why the photos are still here ; now that they drifted apart, they are the only way he have to remember those good times.
Or you can do it more actively, through a series of short flashbacks. The kind of flashback we would have in such situation. Firstly the moment when the photo was taken, then few major moments in their relationship, that slowly switch, showing the distance growing between them.
In both case you'll tell exactly the same thing to the player, without boring him with a totally useless internal narration. In fact, you'll even tell more, because you'll not rely on a single moment, therefore you'll over to the player an overview of this character youth.