[quote=Summer]
The 23 days was for diseases, I believe.That thing about erasing doesn't make sense...
[/quote]
After it says all the information it adds on "But", going on to say the death note can only operate within 23 days, which seems to imply that there isn't exceptions to that 23 day thing as far as the death note is concerned. It the 23 day rules strictly applies to disease it could have been phrased much better to say "any disease can go as far as 23 days", not saying "The death note can only go 23 days". Of course it could just be a poor English translation, but it makes sense that way over allowing someone to become immortal by writing their death at any time it's convenient. If that was possible you would think any number of the characters, especially Light, would have thought of that.

To further prove the point, in synopsis of a movie that I found dealing with writing your name in the Death Note it indeed says that L writes "L Lawliet will die 23 days from this date". He obviously was under the impression that the 23 day rule works for everything or else he would have almost certainly not killed himself off at that time. Not that I'm using movies as canon for the manga, but that seems to imply how it would work for the manga as well in this instance if L had actually done that.

The death eraser was before the rules were all thought up when it was just a concept, so it made sense at the time even if it was a lame idea that is good it was changed.

[quote=ruronihs]
Ok, I'mma solve the N problem right now. He got bored with detective work and used his keen intellect to become the CEO of a the world's largest toy company and has never been happier since. lol.
[/quote]
I'll go with that too. Or we can say he did write his name in the Death Note and offed himself that way some time after the manga ended.