user307: As the title says, and I have a concrete example in mind, g5 attack against the Italian:
[FEN ""]
1. e4 e5 2. Nf3 Nc6 3. Bc4 Nf6 4. d3 h6
5. O-O d6 6. c3 g5

Which can go like this:
[FEN ""]
1. e4 e5 2. Nf3 Nc6 3. Bc4 Nf6 4. d3 h6
5. O-O d6 6. c3 g5 7. Re1 g4 8. Nfd2 h5
9. Nf1 h4

It is a really interesting opening and probably results in some beautiful attacks; however, it violates so many opening principles:

Black does not develop pieces
Black does not get their King to safety
Black makes a lot pawn moves in the opening

The reason we learn about opening principles is that they work in most situations, could playing this opening mess with a players judgement in an unknown position? Would the answer differ depending on a player's level?

user17448: Probably I did not fully understood the question but if you just violate principles, either:

you are on your way on learning them so you should follow them, use
and understand them to know when its OK to break those

or you already know them but you have your reasons (like confusing
lower rated opponent, or surprise someone in a blitz game, etc.) to
violate those in the specific situation


From this I can conclude that playing opening that violates principles by itself will not hurt your level of positional understanding but obviously it will not serve as big improvement either as best improvement of skills can be achieved by using them.
First - learn skill then apply it or make exception as necessary - rule applicable not only here.

user18809: I'd say the opposite is true. "Principles" are great as general rules, but if chess were about following a set of fixed rules, you could simply buy a book that contains those rules and become a Grandmaster after you've finished it.
But that's definitely not the case. Chess is a game of exceptions. Learning about this opening will help you find moves like these (which are actually good moves) in positions where you should play them instead of the "principle-like" moves a beginner would do.
Finally, as the other answer has pointed out, whether or not these moves break the "principles" depends on what you consider the principles to be.

user9684: Generally speaking, violating positional elements, at any time, is bad for positional understanding.  When you win a lot of games with bad positional play, this provides positive reinforcement for playing badly.
This opening, often called the Black Bear of the Philidor, isn't really breaking the opening principles.  Black has gained space on the kingside, has equal control of the center, is just as developed as white (especially considering that there's no good places to put the bishops), and the king is safe as long as the center remains mostly closed.
Great players know when to break the rules.  https://www.chessgames.com/perl/chessgame?gid=1282302

307: <p>As the title says, and I have a concrete example in mind, g5 attack against the Italian:</p>
<pre><code>[FEN &quot;&quot;]
1. e4 e5 2. Nf3 Nc6 3. Bc4 Nf6 4. d3 h6
5. O-O d6 6. c3 g5
</code></pre>
<p>Which can go like this:</p>
<pre><code>[FEN &quot;&quot;]
1. e4 e5 2. Nf3 Nc6 3. Bc4 Nf6 4. d3 h6
5. O-O d6 6. c3 g5 7. Re1 g4 8. Nfd2 h5
9. Nf1 h4
</code></pre>
<p>It is a really interesting opening and probably results in some beautiful attacks; however, it violates so many opening principles:</p>
<ol>
<li>Black does not develop pieces</li>
<li>Black does not get their King to safety</li>
<li>Black makes a lot pawn moves in the opening</li>
</ol>
<p>The reason we learn about opening principles is that they work in most situations, could playing this opening mess with a players judgement in an unknown position? Would the answer differ depending on a player's level?</p>
 17448: <p>Probably I did not fully understood the question but if you just violate principles, either:</p>
<ul>
<li><p>you are on your way on learning them so you should follow them, use
and understand them to know when its OK to break those</p>
</li>
<li><p>or you already know them but you have your reasons (like confusing<br />
lower rated opponent, or surprise someone in a blitz game, etc.) to<br />
violate those in the specific situation</p>
</li>
</ul>
<p>From this I can conclude that playing opening that violates principles by itself will not hurt your level of positional understanding but obviously it will not serve as big improvement either as best improvement of skills can be achieved by using them.</p>
<p>First - learn skill then apply it or make exception as necessary - rule applicable not only here.</p>
 18809: <p>I'd say the opposite is true. &quot;Principles&quot; are great as general rules, but if chess were about following a set of fixed rules, you could simply buy a book that contains those rules and become a Grandmaster after you've finished it.</p>
<p>But that's definitely not the case. Chess is a game of exceptions. Learning about this opening will help you find moves like these (which are actually good moves) in positions where you should play them instead of the &quot;principle-like&quot; moves a beginner would do.</p>
<p>Finally, as the other answer has pointed out, whether or not these moves break the &quot;principles&quot; depends on what you consider the principles to be.</p>
 9684: <p>Generally speaking, violating positional elements, at any time, is bad for positional understanding.  When you win a lot of games with bad positional play, this provides positive reinforcement for playing badly.</p>
<p>This opening, often called the Black Bear of the Philidor, isn't really breaking the opening principles.  Black has gained space on the kingside, has equal control of the center, is just as developed as white (especially considering that there's no good places to put the bishops), and the king is safe as long as the center remains mostly closed.</p>
<p>Great players know when to break the rules.  <a href="https://www.chessgames.com/perl/chessgame?gid=1282302" rel="noreferrer">https://www.chessgames.com/perl/chessgame?gid=1282302</a></p>
