Do you use this scale for ALL VN that you play or do you create exceptions in rare cases?
In situations like this would you forgive some (flaws?) of the game and put more weight of your decision into it's story / concept?
You know what the biggest problem is when most people rate a Visual Novel? Most people get enticed by some of the stronger aspects of a Visual Novel and that leads them to limit their focus on how the Visual Novel as a whole synthesizes. Many people may think/say they rate VNs on an overall basis but most of the time that's not the case because certain aspects of a VN stood out to them without them realizing it.
So, regarding flaws in certain areas.. The reason I focus on both Story/Concept more is because if any of the two have a flaw then that affects Gameplay/Art regardless. For instance you could then have a beautiful looking VN with loads of content lacking in viable concept because it may have been deterred along with its story. Sure, it can be linear if it wants, it just needs to back it up with a few overwhelming things, and in many cases it's the story. Sometimes though you get a VN with a focus on gameplay with great art but an okay story with a sluggish concept, this is a VN that aims to attract you to its gameplay and art, but it can get a high score if said gameplay is reinforced in some way.
To be honest, for a few VNs I sometimes consider them "spammers". I know there's a phrase for it, but I like the word 'spammers' better because it makes perfect sense. These are VNs which try to pack in very nice art with a bland story and spam content like no tomorrow. Many people fall for that for certain reasons and I can see why, but that's not what I look into unless it truly was "overwhelming" and suffices with a nice concept; I've yet to see any 'spammers' that fulfill that ideal. In many cases, 'spammers' also drag the story along and when that happens it affects side routes as well, on purpose, to elongate those corresponding VNs.
Since I rate on emphasis of Story/Concept.. Although a VN may lack in one area, if its Story/Concept is superior then I do make a minor exception. However, if it doesn't lack but literally fails in one area yet is superior in another, then I don't make an exception and I rate based on that. It can't simply fail, it has to at least be "okay."
Extra:
If you look at the ones that I have higher ratings on, I should've just given them at least a 9/10 instead of being a jerk, right? Well, I can't do that, because I've played many VNs, I've read many stories in books and I'm a writing hobbyist as well. The fact that I'm also a gamer isn't ignored when judging VNs. If Clannad's scenarios, or Ever 17's story, or the ending of the Berserk anime doesn't even brush my emotions, then that forces many stories to work with their concept. Considering all those elements, I then judge a VN as an individual. It may be a harsh way to judge but I do take into account what other people view the stories as and how unique it is to its trade, only slightly limiting my expectations although my expectations are a part of it. If I didn't do that, I'd be biased, but since I do, it levels the playing field for a VN's rating.
There is no VN that can be described as "Great" in all categories of Story, Concept, Gameplay, and Art as far as I know.
If you can tell me of a VN that you think is 9/10 in its story, 9/10 in its idea or its uniqueness with the story, 9/10 in its contents or artistic value pertaining to that particular VN, and with at least one of those areas receiving a perfect score of 10/10 please let me know, because that is a great VN in all areas of the experience.
There are only VNs in existence which are simply superior in a few areas and adequate in others rather than superior in a few areas and great in others.
That's why no VN has been given my personal 9/10 rating, yet.
An ideal VN.. Let's look at a simple example of my personal ideal.
Ideal Story:
It has to work well with the concept, it needs to have a certain drive, it needs to teach the player something and ponder certain ideas that are within the VN, it doesn't matter whether or not its fiction/non-fiction, it just has to work well.
Ideal Concept:
Its concept can be simple yet it should be complex and like no other. A concept that needs to work well with its story; original. It shouldn't be hard to come up with a concept that is complex and be like no other, I just thought of a few after thinking about it for 10 seconds. In this world, from the day we are born, we are born without one of the senses, in this world, if our parents do not the sacrifice one of our senses, we will not be given life, and in this world, the senses that are sacrificed from birth are forever lost to us, never returning.
See how simple yet unique that is? Give me 10 minutes and I can already come up with a better concept and great story to work well with it, heck, hire some CG artists, and if I direct the animation team this could be the start of a VN. Wow, I'm motivated but I don't have the necessary time, need to get through college first.
Ideal Gameplay:
Abundant content, non-linear, but if it's linear it has to be backed up, there are some VNs which make up for being linear. Things that can be answered through any extra features. Only if necessary, if the VN just slaps it on then that's not ideal.
Ideal Art:
Something along the lines of detail such as this, and this is digital art too. This is just one example, there are many different examples from various digital artists.
This is one simple explanation of an ideal Visual Novel. And this is why it would be unfair to judge all Visual Novels based on ideals.