Hi there and welcome! Great questions, I am going to enjoy this one.
1. When you have this private playlist playing on a single device throughout the day these views are being counted towards the views for each video, but there are caveats to this. Not all views carry the same weight. I am assuming that the videos themselves are public and that it is the Playlist that is set to Private. In that circumstance these will count as public views (more on that in a moment). So they do count towards the analytics for these videos. But...
A. Playlist/Binge views will only technically count for the first hour. If you are not clicking each and/or hitting the like button, leaving a comment or otherwise engaging with the platform after one hour
the views will count as views but they will not be monetized and you do not get credit for the watch time on the videos that play after that first hour.
B. There are diminishing returns when it comes to views from the same source. I don't know the exact math for this, but simply put when an account watches a video a second time that view is valued at about half the value of the first view. The third is worth about half the value of the second view, and so on. While these still count as views their representation in the YouTube Search and Discovery systems is worth less and less with every subsequent view.
C. If you are watching from the account that hosts the YouTube channel which published that video YouTube sees this as well, and these views are going to be categorized as such. So they will not be as valuable as a video which is watched from another viewers account.
If these videos are set to Private or Unlisted then they do still count... but not towards any meaningful metric. They are not counted as Public Views, which are those gained through public traffic sources. So these views do not count towards monetization, they don't count towards the watch time or retention of that video.
2. If the Playlist itself is Private but the videos are public this makes near-zero difference to your channel because of everything listed above. If both the Playlist and the Videos are set to Private then it makes zero difference to your channel.
So to put a nice bow on this conversation... there is nothing wrong with this but don't expect it to do anything to help your channel either.